Ditherington Flax Mill Shrewsbury, England

The Industrial Revolution gave rise to a new building type: the factory, where a managed workforce could operate machines that were driven by steam power. The advent of machines also created a demand for iron to be produced on a large scale; in addition to being used to build machines, it soon became apparent that iron could be used to construct industrial buildings. The forerunner was the prefabricated cast-iron bridge at Coalbrookdale, England, of 1775–1779. But the factories, especially textile mills, involved problems other than the structural ones. Because they handled large quantities of cotton, flax, and wool, and because their wooden floors were quickly saturated with the oil used to lubricate the machines, they presented a fire hazard. The earliest textile mills had timber floor and roof framing and solid masonry external walls. Cast iron was non-combustible, and it was believed that it offered, as well as greater strength, a measure of fire resistance. Designed in 1795 and built the following year by the

engineer Charles Bage of the milling firm of Bennion, Bage, and Marshall, the Ditherington Flax Mill, in the Shropshire town of Shrewsbury, was the world’s first iron-framed building, the predecessor of most modern factories and even office blocks.

Ditherington was the largest flax mill of its day and one of the largest textile mills of any kind in Britain. The five-story building has conventional load-bearing masonry external walls with very large windows. Internally, it is divided into four bays by three rows of slender, cruciform-section, cast-iron columns, extending for eighteen bays on a north-south axis. Each bay measures about 10 feet (3 meters) square, and the average ceiling height is about 11 feet (3.4 meters). The columns support cast-iron beams spanned by the brick vaults that form the floor above.
The nearby warehouse and cross mill, also iron framed, were built soon after. In 1846 Professor Eaton Hodgkinson published Experimental Researches on the Strength … of Cast Iron, a definitive work that established a design methodology for cast-iron structures; together with Sir William Fairbairn he made a major contribution to the theory of nineteenth-century bridge construction. Cast iron is not fireproof; in fact, it fails structurally and rather dramatically at relatively low temperatures. Consequently, the designers of later iron-framed buildings found ways to protect the columns, often by encasing them in non-load-bearing masonry.
The Ditherington Flax Mill survives, reasonably intact. In 1886 the mill ceased operations, and the building was vacant for ten years. For another century, probably because it had large expanses of open floor space, it was converted to maltings for a brewery. It was empty again from 1987, when the brewery closed down, and has been quite badly vandalized since. In the mid-1990s proposals were put in hand for the refurbishment of all the buildings on the site, with the help of a grant from English Heritage. The project included the creation of shops, restaurants, a heritage information center, leisure facilities and offices, an art gallery, and some housing. In March 2000 Advantage West Midlands announced a £2.8 million (U.S.$4.1 million) grant for the restoration of the mill.

Further reading

Briggs, Asa. 1979. Iron Bridge to Crystal Palace: Impact and Images of the Industrial Revolution. London: Thames and Hudson.

Jones, Edgar. 1985. Industrial Architecture in Britain: 1750–1939. New York: Facts on File.

Mantoux, Paul. 1983. The Industrial Revolution in the Eighteenth Century: An Outline of the Beginnings of the Modern Factory System in England. Chicago: University of Chicago Press.

Deltaworks The Netherlands

The Deltaworks comprises a series of audacious engineering projects that effectively shorten the coastline of the southwest Netherlands by about 440 miles (700 kilometers), seal outlets to the sea, and reinforce the country’s water defenses. Taking more than forty years to complete, the works involved the construction of huge primary dams totaling 20 miles (30 kilometers) in length, in four sea inlets between the Western Scheldt and the New Waterway, Rotterdam.

The Netherlands is located in the broad deltas of the Rhine, Maas, and Scheldt, and the small country’s history and geography have been greatly influenced by a continuous struggle against the rivers and the sea. Through the coincidence of several events in 1953, the southwestern provinces suffered huge floods in which nearly 2,000 people died and thousands of homes were destroyed. The central government quickly reacted, and the Ministry of Transport, Public Works, and Water Management set up the Delta Committee to devise measures to avert a future disaster. The plan informed the Delta Act of 1958, but its implementation, placed in the hands of a complex instrumentality known as Delta Service, took over four decades to complete.
The major elements of the plan were achieved in the following order: the Hollandse IJssel storm flood barrier (1954–1958), the Zandkreekdam (1957–1960); the Veerse Gatdam (1958–1961); the Grevelingendam (1958–1965); the Volkerakdam (1955–1977); the Haringvlietdam (1956–1972); the Brouwersdam (1963–1972); and the Oosterschelde storm flood barrier (1967–1986). The vast scope of the Deltaworks cannot be fully described here, but it may be measured by a brief overview of the largest, most difficult, and most expensive phase: the Oosterschelde (Eastern Scheldt) storm, flood barrier, immodestly referred to by its builders as “the eighth world wonder.”
It was originally intended to close off the Oosterschelde with a permanent dam, and work started in 1967. By 1973 joining das between parts of the coast had closed 3 miles (4.8 kilometers)—more than half—of the river mouth, and three sluices had been built. Then, in response to public protests, it was decided to construct a storm flood barrier instead of completely closing the estuary. Huge concrete pylons standing on the river bottom would support gates that could close to resist storm surges; a concrete roadway would cross the structure. The government signed a contract with the consortium De Oosterschelde Stormvloedkering Bouwkombinatie in 1977. A 3,000-yard-long (2.78-kilometer) access bridge was built to the 50-foot-deep (15-meter)

construction docks needed to fabricate the massive pylons. Commenced in April 1979, the first was finished early in 1983. In the meantime, work began on the sliding gates. Fifty-foot-deep foundations were prepared to support the pylons, and a special dredge was designed to secure the estuary floor against uneven scouring. By the end of 1982, the river bottom was secured by vast mats laid by purpose-designed vessels. All was ready for placing the pylons.

The construction docks were flooded and the pylons, each weighing 21,600 tons (18,300 tonnes) and between 100 and 135 feet (30 and 40 meters) high, were floated into position, then sunk to the prepared floor. Sixty-five pylons formed the spine of the barrier: sixteen in the northern opening, seventeen in the central, and thirty-two in the southern. They were connected by prefabricated elements, and the sliding gates, each 150 feet (45 meters) long and weighing 1,440 tons (1,220 tonnes), were then installed, a task that took a little under two years to complete. Then followed the fixing of each of the sixty-two 3,000-ton (2,270-tonne) precast concrete elements that carried the roadway across the barrier. The Stormvloedkering Oosterschelde was officially opened on 4 October 1986. It cost about a sixth of the 11 billion guilder (U.S.$5.5 billion) total of the Deltaworks.
The danger of overflowing rivers in the winter and early spring also threatens large parts of the Netherlands. Several inland engineering works—the Philipsdam (1976–1987); the Oesterdam (1977–1988); the Markiezaatskade (1980–1983); and the Bathse Spuikanaal and Spuisluis (1980–1987)—were adjuncts to the primary dams of the Deltaworks.
Holland’s struggle against the water continues. Despite the pleas of regional and local water authorities for river dike reinforcement, the national government concentrated its funding for forty years upon the Deltaworks. Moreover, conservationists oppose any dike improvements that would spoil the landscape. The Boertien Commission was established early in the 1990s to address potential problems, and it produced the Great Rivers Delta Plan, which involved reinforcing nearly 190 miles (300 kilometers) of river dikes and embankments. The first phase was completed by the end of 1996; the second, covering another 280 miles (450 kilometers), was finished by 2001. But that will not solve the problem; if nothing else is done, the next generation of Hollanders will have to raise the dikes again. Climate changes, deforestation, urbanization, and drainage in their upper reaches mean that the river systems will carry increasingly large peak volumes. Cooperative policy and water management must be integrated internationally, from the sources to the deltas.

See also

Afsluitdijk; Storm Surge Barrier

Further reading

Boermans, Anne, and Herman Hoeneveld. 1984. English summary of Tussen land en water: Het wisselende beeld van de Deltawerken. Amsterdam: Meulenhoff.

Haan, Hilde de, and Ids Haagsma. 1984. English summary of De Dettawerken: Teckniek, politiek, achtergronden. Delft: Waltman.

Meijer, Henk, ed. 1998. Het Deltaplan in beeld. Utrecht: IDG.

Deal Castle Kent, England

Deal Castle, built in 1539–1540 to stand guard over the town of the same name on the Kent coast of southeast England, is a fine example of a new building type, created in response to major changes in politics. Deal is the largest, most impressive, and most complicated of the so-called Device forts. It probably looks just as was intended: crouching in wait low above the beach, stocky, powerful, and seemingly impregnable.

In the turbulent years that followed Henry VIII’s accession in 1509 he twice made war on France, the second time as an ally of the Holy Roman Emperor. Charles V of Spain. When he realized that France’s defeat would give Spain too much power, Henry changed sides, joining France and the pope against the empire. England was financially ruined by the campaigns of 1527–1528, and six years later, Henry’s divorce from Catherine of Aragon led to a break with the Catholic Church, isolating him from most of Europe. He tried to drive a diplomatic wedge between France and Spain, but in 1538 they signed a truce, arousing Henry’s fear of a joint invasion. He urgently launched an ambitious defense program. Using funds plundered from the monasteries by his religious “reforms,” in 1539 Henry initiated a chain of about thirty forts and batteries to defend England’s major ports and repel the expected invasion fleet. They included ten Device forts: Portland, Pendennis, and St. Mawes in southwest England; Hurst, Calshott, and Sandgate around the Solent; and Camber, Walmer, Sandown, and Deal on the southeast coast.
The nature of warfare was changing, and the sophisticated defense systems of medieval castles had become obsolete. Built to resist mechanical artillery, they now had to withstand, missiles shot with gunpowder. The clumsy bombards of the fifteenth century could be fired only a few times an hour. But by the early sixteenth century cast-iron cannonballs had replaced stone; powder quality had improved; and ordnance was generally smaller, reliable, and accurate. In 1386, Bodiam Castle in Sussex was among the first to replace archers’ loopholes with cannon and gun ports. The decline of feudalism also had its effect: enemies were more likely to be foreign than envious neighbor barons.
Finished late in 1540 Deal, Walmer, and Sandown completed the metamorphosis from medieval castle to modern artillery emplacement. Each of these squat, powerful-looking “castles in the Downs”—they were still called castles—comprised rounded bastions radiating from a circular keep. Their thick walls were curved to deflect cannonballs, and their many gun ports were widely splayed for easy traverse. There were three tiers of cannon for long-range offense and two tiers of defensive armaments. Built by an army of workmen at a total cost of £27,000—1,000 years’ pay for an artillery officer—and joined by earthen bulwarks (since vanished), they formed a defensive cluster along a vulnerable 2-mile (3.2-kilometer) stretch of coast. Sandown has succumbed to coastal erosion, and Walmer has been converted to a residence for the Warden of the Cinque Ports. Only Deal, overlooking the low-lying marshlands, has been conserved.
Henry VIII’s sexual notoriety has overshadowed his considerable abilities as a scholar, poet, and statesman. He took an interest in military engineering and personally amended the proposals for his forts, and the “device” (that is, the design) of Deal Castle has been attributed to him. The temptation to compare the concentric plan to the Tudor rose (as many have done), although alluring, must be resisted. Built with stone quarried from a nearby Carmelite priory, the castle’s architectural form was primarily constrained by serious military purpose: to pack the maximum firepower into the most compact possible structure.
Six semicircular bastions, with curved parapets and bristling with gun emplacements, radiate in two tiers from a central, cylindrical barracks-keep; the configuration is repeated in the surrounding moat. The upper tier abuts the tower; the lower forms the curtain wall. The concentric layout allowed ordnance to be effectively positioned and fired simultaneously without impeding each other. Almost 200 openings penetrate the massive walls at five levels, including 119 cannon ports and embrasures. The remaining loopholes and casemates, mostly at the lower levels, were for arquebuses and pistols. Gun positions within the bastions were vented to clear the smoke and gases. It is easy to imagine the withering salvo afforded by such purposeful design, but it has been suggested that Henry was unable to find enough cannon to fully equip his fortresses.
Because architects usually build upon what they know, Deal, simply because it had evolved from the

medieval castle, also employed traditional defenses. The entrance was at second-floor level and approached by a drawbridge across the moat; attackers then faced a portcullis, beyond which there were heavy, iron-studded oak doors. The gatehouse ceiling was penetrated by five “murder holes” (gun slots for small arms), and a cannon protected an inner door. In the manner of earlier keeps, the central tower was self-sufficient: its basement had supply and ammunition stores and a well. The garrison was quartered at ground level, with a mess hall with fireplace and bake ovens. The upper story housed, rather more comfortably, the captain of the guard.

The anticipated Catholic assault never came. Although Deal was again readied in 1588, this time to repulse the Spanish Armada, once more no invasion eventuated. Late in the English civil war the fortress was held briefly by the Royalists, but they surrendered after a sustained bombardment. In the eighteenth century Deal’s parapets were altered (some say disastrously) in unfulfilled expectation of attacks during the French Revolution, and again during the Napoleonic Wars. No shot was fired in anger until the German bombing of 1941. Since 1984 Deal Castle has been in the care of the Department of the Environment (now English Heritage).

See also

Dover Castle

Further reading

Morley, B. M. 1976. Henry VIII and the Development of Coastal Defence. London: H.M.S.O.

O’Neil, Bryan H. 1966. Deal Castle, Kent. London: H.M.S.O.

Saunders, Andrew D. 1982. Deal and Walmer Castles. London: H.M.S.O.

nd the technology of warfare. With others at Walmer and Sandown, it epitomized Henry VIII’s new forts

De Stijl

Founded in Leiden, the Netherlands, in 1916, the group known as De Stijl was Europe’s most important theoretical movement in art and architecture until the mid-1920s, when leadership passed to Germany.

In 1916 the architect J. J. P. Oud met the critic and painter Theo van Doesburg and soon introduced him to another young architect, Jan Wils. First forming De Sphinx artist’s club in Leiden, the three founded, with the railwayman-philosopher Anthony Kok and the painters Piet Mondrian, Bart van der Leck, and expatriate Hungarian Vilmos Huszár, the group known as De Stijl. Others joined them: the fiery Communist Robert van ’t Hoff and the Belgian sculptor Georges Vantongerloo (both in 1917); the furniture

designer Gerrit Rietveld (1918); the architect Cor van Eesteren (1922); and the painter César Domela (1924). Later arrivals were balanced by departures.

The first manifesto was issued in November 1918, though not all the members signed it. Therefore, De Stijl should never be thought of as a group in the sense that, say, the Pre-Raphaelites or the Impressionists were groups. The members never reached unity of purpose; there were no meetings; and membership seems to have lain in contributing to De Stijl, a polemical journal jealously conducted by van Doesburg. He stretched and frayed their fragile ties by personality issues, and the whole fabric unraveled as members withdrew one by one, unable to work with him. Van der Leck lasted only until 1918; Wils and van ’t Hoff left in 1919; Oud and Vantongerloo two years later; and Mondrian in 1925. Others briefly established links with van Doesburg, but after 1925 only he was left to continue the magazine, by then published only spasmodically. He died in 1931.
Many De Stijl members were influenced by Theosophical doctrine and, subscribing to a holistic worldview “in which the geometric [was] the essence of the real,” they sought unity within the arts and between art and society. Perhaps because its mysticism, religion, and philosophy offered a palliative for the problems of burgeoning capitalism, Theosophy appealed to many in the industrializing world at the fin de siècle. Socialism was an important factor at the time of De Stijl’s birth and for some members social issues were all. They so concerned van ’t Hoff that, unwilling to work for middle-class clients, he soon forsook architecture altogether. Seeking an appropriate architecture, the others explored Constructivism, temporarily preached Neoplasticism, and generated what Oud called Cubism, but theory seldom extended to architectural realities. The few realized projects were spectacular: van Doesburg’s Café Aubette, Strasbourg (1926–1927, with Jean Arp and Sophie Taeuber-Arp), carried “painting into architecture, theory into practice.”
Rietveld’s Schröder house demonstrated De Stijl ideas and became an icon of European Modernism. In 1921, Rietveld began to collaborate with the interior designer Truus Schröder-Schrader. The tiny house in Utrecht (1924) that he designed for her expresses, more than anything else undertaken by the group, the principles valued by De Stijl. Earlier, Rietveld had collaborated with his De Stijl colleagues on fragments of schemes and unrealized projects. What they had been able to only dream of or explore in scale models, Rietveld built as his first complete architectural work.
The division among Dutch architects on religious and political grounds prevented wider acceptance of De Stijl’s ideas within the Netherlands. De Stijl became an international journal (or rather, by van Doesburg’s duplicity, an illusion of one), and through its pages and his personal preaching he shared with Europe the message of an architectural climax. De Stijl was moribund when van Doesburg died in 1931, but for a moment or two, through it, the Dutch had supplied a lot of theoretical and rather less practical input to modern architecture. Not least, by commenting upon his work to a wide audience, they provided a gateway for Frank Lloyd Wright’s “peaceful penetration of Europe.” In 1936 Alfred Barr of the New York Museum of Modern Art perceptively remarked that De Stijl had overshadowed German architecture and art in the mid-1920s. Moreover, had van Doesburg’s attempted insinuation into the Dessau Bauhaus succeeded, that critically important school of architecture and design would have been turned toward Russian Constructivism.

Further reading

Blotkamp, Carel, ed. 1986. De Stijl, the Formative Years, 1917–1922. Cambridge, MA: MIT Press.

Friedman, Mildred, ed. 1982. De Stijl, 1917–1931: Visions of Utopia. New York: Abbeville Press.

Overy, Paul. 1991. De Stijl. New York: Thames and Hudson.

De Re Aedificatora

Leon Battista Alberti’s theoretical treatise on architecture, titled De Re Aedificatoria (About Buildings), was dedicated in 1452 but not published until 1485. What qualifies it as an architectural feat? It changed the understanding and practice of architecture in much of Europe and continued to influence developments there and in the New World for about 400 years. Although he was gathering the ideas for the book, Alberti (1404–1472) was not an architect but a Catholic priest.

Alberti was born in Genoa, the illegitimate child of Lorenzo, an exiled Florentine from a family of bankers. When he was about ten years old, Battista (he added “Leon” later) entered a boarding school in Padua to receive a basic classical education. Several years of legal studies at the University of Bologna led to a doctorate in church law in 1428, after which he went to Florence. He soon began writing. His first published anthology of poems, Il cavallo (The Horse) of 1431, was quickly followed by Della famiglia (About the Family)—the first of many philosophical dialogues—and La tranquillità (Composure), a collection of essays, short stories, and plays, both in 1432. By then he was employed as a secretary in the Papal Chancery in Rome and was about to undertake a lives of the saints and martyrs, written, as was fashionable, in classical Latin. Living in Rome opened Alberti’s eyes to classicism, although the city was to remain neglected for another fifteen years. In 1434 he wrote a study about urban design entitled Descriptio urbis Romae (Description of the City of Rome), in which he first explored the classical notion that beauty existed in harmony, achievable through mathematical rules.
Alberti’s future lay not in the law but in the church. Taking holy orders, he would eventually become a canon of the Metropolitan Church of Florence in 1447. Other clerical offices and their benefits followed: abbot of San Sovino, Pisa, Gangalandi Priory, Florence, and the rectory of Borgo San Lorenzo in Mugello. In 1436 he completed his first major book, written in classical Latin, that touched upon architecture: De pictura (About Painting) was an attempt to bring system to perspective and set down rules for the painter to achieve concord with cosmic harmony. An Italian translation appeared in the same year.
From about 1434 Alberti traveled through northern Italy in the retinue of Pope Eugenius IV, visiting Florence, Bologna, and Ferrara, where, in 1438, under the patronage of Marchese Leonello, he began a more careful study of classical architecture, delving into the ten-part book De Architectura, written by one Marcus Vitruvius Pollio around 20 b.c. Alberti returned to Rome six years later and extended that study among the ancient buildings. When Nicholas V succeeded to the papacy in 1447, Alberti was appointed inspector of monuments, an office he held

until 1455. De Re Aedificatoria, written in classical Latin and structured in ten parts like Vitruvius’s De Architectura, was completed in 1452. Vitruvius’s book was its principal source and model, but Alberti also drew upon Plato, Pythagoras, and the Christian fathers; his own archeological studies; and, importantly, the consensus of contemporary architectural thought. Vitruvius had summarized the architectural practice of his day; Alberti went further to lay down universal rules.

As Italian society and fashions changed, from around 1420 the mason-architect had begun to be displaced, first by the artist-architect and then the courtier-artist-architect. With training in neither building nor art, Alberti wrote a book about the art of building that completed the metamorphosis of the architect into a dilettante-scholar; that made “design distinct from matter,” as he put it, and turned the art of architecture into an academic pursuit in which creativity and design skill could be honed to perfection simply by obeying a set of rules. Intuition was replaced with measurable absolutes. It gave architectural design a thoroughly developed theory of harmony and proportion and made it simple—at least in theory. According to some sources, the last Latin edition was a folio version in Bologna, of 1782. Translations and many derivative works found their way through western Europe.
Book I of De Re Aedificatoria defined design, set down the criteria for good architecture (convenience, stability, and delight), and discussed the basis of composition and proportion. Book II dealt with matters of professional practice and building materials. Book III addressed practical building construction. Book IV covered many aspects of civic design, and Book V dealt with plans for various building types. The next book explored the esthetic dimension of architecture, defining beauty as “a harmony of all the parts in whatsoever subject it appears, fitted together with such proportion and connection, that nothing could be added, diminished or altered, but for the worse.” It also included a section on mechanical and technical details. Alberti’s strong attachment to antiquity was revealed in Books VII and VIII, that took up the subjects of ornament in religious buildings and Roman urban design, respectively. In Book IX the axiomatic principle underlying Renaissance architecture was restated: that beauty is an innate property of things, achieved by following cosmic rules. Then there was an assortment of chapters about mostly practical issues. Book X descended to the pragmatic: water supply, engineering, repairing cracks, and even how to get rid of fleas.
Alberti applied his theories in only a few buildings, mostly unfinished renovations or extensions. They included the facades of the Church of San Francesco (otherwise known as Tempio Malatestiano) of 1450, in Rimini; the facades of the Palazzo Rucellai (1446–1451) and Santa Maria Novella (1458–1471), both in Florence; and San Sebastiano (1459) and Sant’Andrea (1470–1472), both in Mantua. His biographer Giorgio Vasari wrote in 1550, “His writings possess such force that it is commonly supposed that he surpassed all those who were actually his superiors in art” and added, “He was a person of the most courteous and praiseworthy manners … generous and kind to all.”

Further reading

Alberti, Leon Battista. 1988. On the Art of Building in Ten Books. Cambridge, MA: MIT Press.

Borsi, Franco. 1989. Leon Battista Alberti: The Complete Works. New York: Electra/Rizzoli.

Vasari, Giorgio. 1991. Selections from the Lives of the Artists. Oxford, UK: Oxford University Press.

Curtain walls

Traditionally, the wall of a building served both structural and environmental purposes. That is, it carried to the ground the weight of the building and its contents and, while admitting air and light through openings, protected the interior from extremes of weather, noise, and other undesirable intrusions. The introduction of structures in which the loads are carried by beams and columns liberated the wall from load bearing, allowing it to function solely as an environmental filter—a relatively thin, light curtain, so to speak. This was first seen in the later medieval cathedrals with their vast stained-glass windows, but it would not be widely developed until the nineteenth century, with the advent of metal-framed architecture and, subsequently, reinforced concrete. The metal-and-glass membrane supported by the building frame, known as the curtain wall, is principally associated with multistory office buildings after about 1880.

Although the first skyscrapers, such as the Rookery (1885–1886) and Monadnock Building (1889–1891), both in Chicago and both designed by architects Burnham and Root, had thick conventional load-bearing walls, the twin economic necessities of getting buildings up quickly and optimizing the quantity and quality of interior space soon led to buildings whose outer walls consisted almost entirely of windows supported by perimeter columns and beams. This was a first step toward the development of a true curtain wall, that is, a continuous wall in front of the structural frame. The earliest example was Albert Kahn’s Packard Motor Car Forge Shop in Detroit (1905). A curtain of glass in steel frames allowed more space

and light in the factory, just as it would in an office tower, and Kahn again employed it for the Brown-Lipe-Chapin gear factory (1908) and the T-model Ford assembly plant in Highland Park, Michigan (1908–1909). This rational industrial architecture drew the admiration of Europe and was emulated in Peter Behrens’s A. E. G. Turbine Factory (1909–1910) in Berlin and Gropius and Meyer’s Fagus Works in Alfeld-an-der-Leine, Germany, of 1911.

It is widely accepted that the first office block with a curtain wall was Willis Jefferson Polk’s eight-story Hallidie Building (1917–1918) in San Francisco. Although it was cluttered in places with florid cast-iron ornament, the street facade, suspended 3 feet 3 inches (1 meter) in front of the structure by brackets fixed to cantilevered floor slabs, presented an unbroken skin of glass. Elsewhere, others dreamed of crystal prisms in which the building’s whole external membrane was glass: the serried towers of H. Th. Wijdeveld’s Amsterdam 2000 (1919–1920) and Le Corbusier’s Ville Contemporaine (1922) and—probably best known—the skyscrapers Ludwig Mies van der Rohe projected between 1919 and 1923. But dreams and visions they remained, because the technology was not yet available to turn them to reality. One exception was the A. O. Smith Research Building in Milwaukee (1928–1930) by Holabird and Root, the first multistory structure with a full curtain wall (rather than a single facade) of large sheets of plate glass supported on aluminum frames.
Spin-offs from defense technologies after World War II paved the way for tall curtain wall buildings. Important among them was cost reduction in the production of aluminum, whose corrosion resistance could be improved by a process known as anodizing. This lightweight metal could be extruded into the complicated profiles needed to frame the glass and strengthen the wall against wind loads. Reliable cold-setting synthetic rubber sealants had also become more widely available. These advances were combined with more efficient sheet glass manufacture, especially polished cast glass and, after 1952, the much flatter float glass. Wall elements could be fabricated off-site to exacting tolerances and then transported, assembled, fixed, and glazed with none of the “wet” processes that impede building contracts. Relevant engineering developments included reverse-cycle air-conditioning—available since 1928—and fluorescent lighting, first demonstrated at the 1938 Chicago World’s Fair. All these technologies were exploited in Pietro Belluschi’s twelve-story Equitable Building in Portland, Oregon (1944–1948), described by one historian as “an ethereal tower of sea green glass and aluminum.” Another writer asserts that it “set styles for hundreds that came after.”
The thirty-nine-story United Nations Secretariat Building in New York City followed in 1947–1952. The final design was developed from a proposal by Le Corbusier, and Wallace Harrison acted as executive architect in consultation with him. The curtain walls of the Secretariat Building’s east and west facades are all glass, cantilevered 27 inches (80 centimeters) from the line of the perimeter columns; black-painted glass spandrels hide the between-floor spaces. The blue-green tinted windows are of “Thermopane,” a special glass that absorbs radiant heat, preventing it from reaching the interior, thus reducing the load on the air-conditioning system. The only breaks in the sheer curtain wall are full-width air-conditioning intake grilles at four levels. Because of its innovation, and no doubt because of its associations, the U.N. Secretariat, together with Mies van der Rohe’s Lake Shore Drive Apartments (1951) in Chicago and Skidmore, Owings, and Merrill’s Lever House (1952) on Park Avenue, New York, contributed to the universal standard for high-rise buildings.
The latter building, a twenty-four-story, green-tinted glass and stainless steel tower, designed by Gordon Bunshaft, marked a change of direction in American corporate architecture and in the way New Yorkers built. In keeping with the wishes of a client who made household cleaning products, Bunshaft produced an immaculate, clean-lined tower. The architectural critic Lewis Mumford called it “an impeccable achievement.” The top three floors are reserved for mechanical services. A mobile gantry carries a window cleaners’ platform that serves all faces of the building; such devices became standard for the curtain wall office buildings that followed. Lever House was the first skyscraper to exploit the allowable plot ratios in city planning regulations. By

occupying only a quarter of the site, it allowed much more natural light to enter the offices than conventional stepped-back skyscrapers that covered the whole allotment. Lever House is a New York historic landmark, and in November 1999 a $10.7 million contract was let to renovate its curtain walls, designed by Skidmore, Owings, and Merrill under the supervision of the New York City Historical Society.

That leads us to the inherent problems in curtain wall construction, for all of its advantages. In forty-five years, the pristine facades failed in a number of ways—water penetration and consequent damage, corrosion, and broken glass panels. Since their inception, curtain wall systems have been continually revised, most changes geared toward reducing weight while retaining strength. Stiffened sheet aluminum, enameled steel laminated with insulation, and later even thin sheets of stone were used for spandrel panels. The design of joints—problem spots for leaks—was improved and more durable sealants were invented. More recently, the availability of reliable adhesives has allowed architects to indulge in so-called “fish tank” joints between glass panels, doing away with framing bars. Glass technology has also been refined. Double glazing, first manufactured in the 1940s, improves both the sound and thermal insulation of curtain walls. Heat-absorbing glass, already available in the 1950s, evolved in the following decade into reflective glass with thin metallic coatings, also used to reduce heat gain within buildings. In 1984 heat mirror glass was developed; when combined with double glazing, its insulating value approaches that of masonry, but the esthetic effect seems to be a denial of the form of the building: all it does is reflect what’s around it.
Given that the two significant advantages of curtain wall construction are the reduction of weight and speed of erection, it might be concluded that it costs less than conventional work. That is not necessarily true, because its behavior as an environmental filter, especially in relation to heat flow, may result in higher air-conditioning costs. Often, the preciousness of the architect’s detailing increases costs, as evidenced by Mies van der Rohe’s bronze-and-brown-glass Seagram Building (1954–1958) in New York City. It cost $36 million, approximately twice as much as office towers normally did.
The tall glass prism was the major contribution of the United States to the so-called International Style of modern architecture. But its glorious day passed with the rise of postmodernism, and the crystal towers that Frank Lloyd Wright dismissed as “glass boxes on stilts” were replaced with less anonymous designs. Even Philip Johnson, Mies van der Rohe’s most ardent disciple, forsook the minimalist forms of curtain-wall architecture in favor of a more congenial architecture.

Further reading

Frampton, Kenneth, and Yukio Futagawa. 1983. Modern Architecture, 1851–1945. New York: Rizzoli.

Krinsky, Carol Herselle. 1988. Gordon Bunshaft of Skidmore, Owings, and Merrill. Cambridge, MA: MIT Press.

Stubblebine, Jo, ed. 1953. The Northwest Architecture of Pietro Belluschi. New York: F. W. Dodge.

Wright, Sylvia Hart. 1989. Sourcebook of Contemporary North American Architecture: From Postwar to Postmodern. New York: Van Nostrand Reinhold.

Crystal Palace London, England

The Crystal Palace, a vast demountable building designed by Joseph Paxton for the Great Exhibition of 1851 in Hyde Park, London, was in many ways crucial in the development of architecture: it was the pinnacle of innovative metal structure, it revealed the exciting potential of efficient prefabrication, and it was an early demonstration of the modern doctrine that beauty can exist in the clear expression of materials and function. Altogether, it was one of the most noteworthy buildings of the nineteenth century

The idea for a Great Exhibition came from the Society for the Encouragement of Arts, Manufactures, and Commerce, and was given impetus by Henry Cole, then an assistant keeper in the Public Records Office. His wide interests extended to the publication of The Journal of Design that encouraged artists to design for industrialized mass production and urged manufacturers to employ them. That, he believed, would raise the quality of everyday articles. Cole was elected to the society’s council in 1846, and the following year, with others, he successfully solicited Queen Victoria’s consort, Prince Albert of Saxe-Coburg-Gotha, to accept the role of its president. Under Royal Charter, and spurred by the success of French industrial expositions since 1844, the society held Exhibitions of Art Manufactures from 1847 through 1849.
After visiting the exclusively French exhibition in Paris in 1849, Cole realized that an international show would inform British industry of progress (and commercial competition) elsewhere in the world. Prince Albert, convinced that “that great end to which all history points—the realization of the unity of mankind” was imminent, caught the vision. The Royal Commission for the Exhibition of 1851 was established to expedite a self-financing “large [exhibition] embracing foreign productions.” It was envisioned as “a new starting-point from which all nations will be able to direct their further exertions,” but it was at the same time an expression of British nationalism. Britain had led the world into the Industrial Revolution, and her outlook was smug, to say the least. The Great Exhibition would provide a vehicle to flaunt her industrial, military, and economic superiority and justify her colonialism.
The show was to have a display area of 700,000 square feet (66,000 square meters), much bigger than anything the French had managed. That was too large even for the intended venue in the courtyard of Somerset House, so it was decided to locate it in Hyde Park. An open competition for the design of a building for the “Great Exhibition of the Works of All Nations” attracted 245 entries from 233 architects, including 38 from abroad. The Commissioners’ Building Committee liked none of them; besides, it was unlikely that any could have been completed on

time. Having prepared its own plan for a large dome standing on a brick drum, the committee called for bids. The result was alarming: building materials alone would have devoured at least half of the available funds of £230,000. Anyway, the design was generally considered ugly, especially by the architects whose proposals bad been rejected.

Fox and Henderson and Company, a firm of contractors, engineers, and ironmasters, tendered a price for an alternative, based on a design by the gardener Joseph Paxton. In 1826 Paxton had been appointed head landscape gardener at Chatsworth, the Derbyshire estate of the sixth Duke of Devonshire. He built large conservatories there, including one in 1886–1840 for the giant water lily, Victoria regia. Paxton claimed that his design for the Great Exhibition building was inspired by the structure of that lily, whose cross ribs strengthened the main radial ribs.
Learning that the invited architects had been turned down, Paxton had sketched out his proposal on a sheet of blotting paper—romantic tradition says it was during a train journey—and through a lucky meeting with a mutual friend he was able to show it to Cole. The idea was simple: a modular structure of a single cross section, built from prefabricated metal components, could be repeated ad infinitum to produce a building of any size. Paxton promised Cole that he would have detailed designs ready within a fortnight. In fact, they were completed in nine days and passed to Fox and Henderson on 22 June 1850. By then, the provision of a building was becoming urgent. Paxton’s proposal had the desirable advantage of rapid construction; moreover, unlike the other schemes, it could later be demounted to leave Hyde Park relatively undisturbed. The commission accepted it; the only modification asked for was a vaulted transept so the building could contain without damage the large elm trees on the site.
The Crystal Palace, as it was soon dubbed, was a single space, 1,851 feet long and 456 wide (554 by 136 meters), rising by 20-foot (6-meter) increments across flanking tiered galleries to a 66-foot-high (20-meter) central nave. It was intersected in the middle by a 108-foot-high (32-meter) vaulted transept. The building covered 19 acres (7.6 hectares) of Hyde Park. A filigree of 330 slender, cast-iron columns and arcades supported its clear glass walls and roofs and the wrought-iron beams that carried the galleries, alternately 24 feet (7.2 meters) and 48 feet wide.
Due largely to Paxton’s consummate organizational skills, Fox and Henderson accomplished its construction between September 1850 and January 1851. The Birmingham glassmaking firm of Chance Brothers supplied almost 294,000 panes, which were fixed in a specially designed roof-glazing system based on economical 49-inch-wide (1.25-meter) sheets that determined the module for the entire design. Building work oil-site consisted mostly of assembling the 3,920 tons (3,556 tonnes) of cast-iron components that came from ninety different foundries throughout Britain, often cast less than a day before they were fixed. The accuracy obtained through prefabrication and the mechanical fixing dramatically reduced the proportion of nonproductive labor common to traditional construction methods. Cast-iron columns were strength-tested, and on-site milling and machine painting included miles of timber-glazing bars. The building was decorated in red, green, and blue, and the columns were brightened with yellow stripes. The Crystal Palace established internationally a style and a standard for exhibition pavilions, next at Cork (1852), then at Dublin and New York (both in 1853), and Munich (1854).
The Great Exhibition opened on 1 May 1851, with more than 13,000 exhibits from around the world. By the time it closed six months later, over 6.2 million people had visited it. Despite popular insistence that the building should remain, it was scheduled for dismantling. A consortium bought it and it was, under Paxton’s supervision, reerected in a modified form in a park designed by him at Sydenham Hill, southeast London. Reopened by Queen Victoria in June 1854, the Crystal Palace became a national center for exhibits of industry, art, architecture, and natural history, all held under the auspices of the Crystal Palace Company. Sporting events took place in the park from about 1857 and for twenty years after 1895 it became the venue for Football Association Cup finals. Motor racing followed in 1936.

park now survives, and even that is under threat. The Crystal Palace Partnership, with representatives of five London boroughs and private-sector groups, is undertaking a £150 million regeneration scheme for Crystal Palace Park that includes its “restoration,” a concert platform, modernization of the National Sports Centre, and a so-called new Crystal Palace on the surviving 12-acre (4.8-hectare) terrace. The latter, an insensitive proposal for a utilitarian building housing a twenty-screen cinema multiplex with restaurants, bars, and rooftop parking for a thousand cars, provoked local residents to launch the Crystal Palace Campaign in May 1997. A challenge to the scheme is being mounted in the High Court on the grounds that the Crystal Palace Act of 1990 provides that any building on the site should be “in the style and spirit of the former Crystal Palace.”

Further reading

Bird, Anthony. 1976. Paxton’s Palace. London: Cassell.

Elliot, Cecil D. 1992. Technics and Architecture: The Development of Materials and Systems for Buildings. Cambridge, MA: MIT Press.

The Great Exhibition: London’s Crystal Palace Exposition of 1851. 1995. New York: Gramercy

In November of that year, the Crystal Palace was destroyed by fire. Only one terrace of the original

.

Coöp Himmelb(l)au

The “maverick Viennese partnership” Coöp Himmelb(l)au (literally, the “Sky Blue Cooperative”) was established in May 1968 by Wolf D. Prix and Helmut Swiczinsky. Their architecture has been called expressionistic, spontaneous, irrational—all characteristic of the Deconstructivism that followed them. Why should they be included in an encyclopedia of architectural feats? Because they were the archetypal challengers, not altogether without success, of orthodox architectural thinking at the end of the twentieth century.

Until the late 1970s, when they took a “technological stance,” drawing “airy therapeutic machines,” their practice focused mainly on interior architecture. Twenty years later they unabashedly aimed to unsettle and create unrest, reacting mostly against

the history-plundering aspects of postmodernism. Such contradiction of what were held to be architecture’s “eternal truths”—harmony, unity, and clarity—must be seen as neo-Mannerism, playing it for kicks, so to speak. Their interior spaces and elements of their facades, thrust through with girders, giant needles, or spikes, create esthetic emotions of discomfort and disturbance rather than once-prized beauty. Someone has described their work as “an architecture of the chest spiked by the steering column.”

Early designs of this kind included the Reiss Bar (1977) in Vienna, whose interior is split by a fissure ostensibly held together by massive turnbuckles. The front door is pierced by two huge spikes. The Red Angel Bar (1980–1981), also in Vienna, uses “tin, steel and glass block [to] embody the form and soul of the hovering angel, the wails of the sinners, and the protests of an antiestablishment youth.” To enclose the space, wings spread out from the diagonal spike that forms the structural spine—a frequent motif in their buildings.
This approach climaxed in a number of projects and buildings, including a prizewinning master plan for the new town of Melun-Senart, near Paris, France (1987), a proposed city center for St. Polten, Austria (1989–1990)—urban design schemes in which the excitement of polemic eventually gave place to the pragmatics of city bylaws—and a hilltop studio for Anselm Kiefer in Buchen, Germany (1990). It can be found also in the Funder Factory 3 in St. Veit/Glan, Austria (1988–1989). There, Coöp Himmelb(l)au “dissolved” what might easily have been a boring long-span industrial shed into “an amalgam of more sculptural, functionally differentiated elements,” with spectacular results: a main building with a red entrance canopy, a power plant with three 75-foot-high (23-meter) chimneys that lurch drunkenly, and an assembly-line building whose corner is an exploding structure of steel and glass. The same dynamism may also be seen in a strangely compatible penthouse addition (1984–1988) to a neoclassical building in Vienna. It has been described as “biomorphic … an exposed exoskeletal structure” whose boardroom looks like a “dissected ribcage.” Outside, it looks very much like a huge beetle with spread wings, scrabbling for a foothold on the roof.
In June 1989 Coöp Himmelb(l)au won (with locally based Morphosis and Burton and Spitz) first prize for a pavilion in a Los Angeles performing arts park. Opening an office in the U.S. city, they secured several commissions in southern California. In 1993 they won a competition for the Jussieu Campus Library of the University of Paris and were commissioned to design the east pavilion of the Groninger Museum, Groningen, the Netherlands, completed in 1995. The following year they represented Austria at the International Architecture Biennale in Venice. They have recently completed the eight-theater UFA Cinema Center in Dresden, Germany (1993–1998), and the SEG Apartment Tower in Vienna, a complex of residential and other towers and a school (1994–1998). Working with a staff of twenty-seven, they undertook a project to convert the shell of a former Vienna gasometer into a multipurpose building; another complex in Hamburg, Germany; an entertainment center in Guadalajara, Mexico; and a building for Expo 2001 in Biel, Switzerland, all between 1995 and 2000.

Further reading

Gruenberg, Oliver, Robert Hahn, and Doris Knecht, eds. 1988. Coop Himmelb(l)au: Power of the City. Darmstadt, Germany: G. Büchner.

Peter Noever, ed. 1991. Architecture in Transition: Between Deconstruction and New Modernism. Munich: Prestel.

Steinbauer, Jo, and Roswitha Prix, trans. 1983. Coop Himmelb(l)au, Architecture Is Now: Projects, (Un)buildings, Actions, Statements, Sketches, Commentaries, 1968–1983. New York: Rizzoli.

Confederation Bridge, Prince Edward Island Canada

The 8-mile-long (12.9-kilometer) Confederation Bridge, which crosses the Northumberland Strait between Jourimain Island, New Brunswick, and Borden-Carleton on Prince Edward Island, is the longest bridge over ice-covered water in the world. Its daring conception, the quality of its engineering, and the logistics of its realization are among the factors that make it one of the great constructional feats of the twentieth century. The project is also environmentally, politically, and culturally significant.

Prince Edward Island, on Canada’s Atlantic coast, is the nation’s smallest province, with a population of around 130,000. It lies in the Gulf of St. Lawrence at an average of 15 miles (24 kilometers) across the strait from mainland New Brunswick and Nova Scotia. The strait freezes for up to three months every year, and links with the island historically were expensive, freight and passengers having to be moved by ferry. In 1912 the Canadian government decided to build a railcar ferry to run between Borden-Carleton and Cape Tormentine, New Brunswick, and the Prince Edward Irland was commissioned in 1917. In the first year she made only 506 round-trips. In 1938, as a response to wider automobile ownership, a car deck was added, and the vessel continued to operate until 1969. The subsequent decades saw improvements to the service, and new ferries now make the seventy-five-minute crossing at hour-and-a-half intervals. Prince Edward Island has become a vacation resort and by the beginning of the 1990s tourism had joined commercial fishing and agriculture as a mainstay of its economy.
Between 1982 and 1986 several consortia approached Public Works Canada (PWC) with proposals for a privately financed permanent link between the island and the mainland. Three were for bridges (the first estimated at Can$640 million), one for a tunnel, and another for a combined causeway-tunnel-bridge link. In December 1986, the central government instructed PWC to commission feasibility studies of fixed-link alternatives. By June 1987 twelve expressions of interest were in hand, and the acceptance of Strait Crossing’s proposal was announced in

December 1992. Strait Crossing Development (SCD), a consortium of Janin Atlas, Ballast Nedam Canada, and Strait Crossing, was established to develop, finance, build, and operate the Confederation Bridge.

The proposal, put before the island population in a plebiscite the following January, was generally supported, but lobster fishermen and conservationists raised concerns that led to protracted delays. Their conservation measures won for the contractors the Canadian Construction Association’s 1994 Environmental Achievement Award. Working with the Canadian Wildlife Service, SCD provided nesting platforms for endangered osprey in Cape Jourimain National Wildlife Area. The consortium also initiated a Lobster Habitat Enhancement Program, using dredged material to establish new lobster grounds in three formerly nonproductive locations. Construction work commenced in mid-July 1995.
The shore-to-shore Confederation Bridge consists of three parts. The 1,980-foot (0.6-kilometer) east approach from Borden-Carleton and the 4,290-foot (1.3-kilometer) west approach from Jourimain Island, New Brunswick, join the 6.9-mile (11-kilometer) main bridge across the narrowest part of the Northumberland Strait. Its two-lane carriageway rises from 120 feet (40 meters) to 180 feet (60 meters) above the water at the central navigation span. The bridge takes about ten minutes to cross at the design speed of 50 mph (80 kph).
Engineers designed for a 100-year life, taking into account the combined severe effects of wind, waves, and ice. In part, this was achieved by using concrete up to 60 percent stronger than normal in construction. The concrete employed in the 60-foot-diameter (20-meter) ice shields, designed to break up the ice flow at the pier bases, was more than twice normal strength. Because climatic conditions limited on-site construction to six months of the year, the bridge was designed to be assembled in the summers from posttensioned concrete components precast during the winters. The parts of the approach bridges were cast at a staging facility in Bayfield, New Brunswick, transported by land or water to the site, and assembled by a twin launching truss with a traveling gantry crane. Another staging facility was set up in Borden-Carleton to precast the 175 main bridge components. Some weigh as much as 8,000 tons (8,128 tonnes); the main box girders are 570 feet (190 meters) long, yet designed to be joined with tolerances of less than 1 inch (2.54 centimeters).
In August 1995 a purpose-built floating crane, the Svanen, began placing the components of the east approach bridge, completing it in November; the west approach was built the following spring. The main bridge followed, and by August 1996 the navigation span was the last to be placed. On 19 November the structure was complete: sixty-five reinforced concrete piers, founded on bedrock, supported the 8-mile (12.9-kilometer) superstructure which curves gracefully across Northumberland Strait. During the next six months, the finishing work—the polymer-modified asphalt cement road surface, traffic signals, emergency call boxes, weather monitoring equipment, closed-circuit television cameras, and toll booths—was carried out, and the bridge was opened on 31 May 1997. The estimated direct construction cost was Can$730 million.

Further reading

Macdonald, Copthorne, 1997. Bridging the Strait: The Confederation Bridge Project. Toronto: Dundurn Press.

Thurston, Harry, Wayne Barrett, and Anne MacKay. 1998. Building the Bridge to P. E. I. Halifax, Canada: Nimbus.

Colossus of Rhodes Greece

One of the seven wonders of the ancient world, the huge statue of the pre-Olympian sun god Helios stood at the entrance to the harbor of Rhodes on the Aegean island of the same name. The work of the celebrated sculptor Chares of Lindos, the giant figure, shown in some representations to be shielding his eyes as he looked out across the sea, towered 110 feet (33 meters) above the entrance to the Mandraki harbor. According to Greek mythology, Helios was the son of the Titans Hyperion and Thea, and brother of Selene, goddess of the moon, and Eos, goddess of the dawn. He was worshiped throughout the Peloponnese, and the people of Rhodes held annual gymnastic games in his honor.

The cast-bronze shell of the Colossus, reinforced and stabilized with an iron-and-stone framework, stood on a white marble base. It has been suggested that, in order to attach the upper parts of the monument, earth ramps and mounds were built. Work commenced around 294 b.c.—although some sources put the date at ten years earlier—and the statue took twelve years to complete. Its size is hard to comprehend, but some idea can be gained from Pliny the Elder, who wrote, “Few people can make their arms meet round the thumb.” From medieval times, artists’ romanticized impressions have shown the Colossus straddling the entrance to Mandraki harbor, towering over the ships that sailed between his feet. Given its height, the width of the harbor mouth, and the technology available to the builders, that construct is most improbable. The fact is that no one knows exactly what the statue looked like, nor where it stood. Recent scholarship suggests that it stood on the eastern promontory of the Mandraki, or perhaps a little inland.
Rhodes was an important island in the ancient civilization of the Aegean. The Dorians inhabited it in the second millennium b.c., and their city-states of Lindos, Camiros, and Ialysos were vigorous commercial centers with colonies throughout the region. In the fifth century b.c., it belonged to the Delian League, a confederacy of city-states led by Athens, ties they severed in 412 b.c. Just four years later their own confederation was celebrated in the completion of the new city of Rhodes, said to have been designed by Hippodamos of Miletus; it seems more likely that it was laid out according to Hippodamean principles.
In 332 b.c. Rhodes came under the control of Alexander the Great, but following his de

years later its citizens revolted and expelled the Macedonians. Rhodes’s power and wealth reached a zenith in the second and third centuries b.c., and it became a famous cultural center. One badge of that political unity and artistic eminence was the Colossus, built to commemorate the raising of the Antigonid Macedonian Demetrios Poliorcetes’ long siege (305–304 b.c.). The metal for the statue was taken from the siege machines abandoned by the invaders when they withdrew. It is said that the dedicatory inscription read, “To you, O Sun, the people of Dorian Rhodes set up this bronze statue reaching to Olympus when they had pacified the waves of war and crowned their city with the spoils taken from the enemy. Not only over the seas but also on land did they kindle the lovely torch of freedom.”

A violent earthquake struck Rhodes about 225 b.c. The city was extensively damaged, and the Colossus, broken at the knee, crashed down. Ptolemy III of Egypt offered to meet the restoration costs, but when an oracle warned them against rebuilding, the Rhodians declined. It is ironic that the Colossus was actually lying in ruins when it was accorded a place among the wonders of the world. In a.d. 654 the Arabs invaded Rhodes, and two years later a Muslim dealer—some sources say a Syrian Jew—bought the fragments of the statue as scrap metal and carried them away to be melted down. Tradition has it that they were transported to Syria by a caravan of 900 camels.
In December 1999 the Municipal Council of Rhodes announced an international design competition for a new Colossus. As the island’s millennium project, the monument will encompass “modern artistic expression and technical construction that will surpass conventional standards [while borrowing] all the ancient symbolic values of the original.” Expected to cost U.S.$2.8 million, it is, intended to be finished in time for the Athens Olympic Games in 2004.

Further reading

Clayton, Peter, and Martin Price. 1988. The Seven Wonders of the Ancient World. London: Routledge.

Cox, Reg, and Neil Morris. 1996. The Seven Wonders of the Ancient World. Parsippany, NJ: Silver Burdett.

ath nine

Colossus Bridge, Schuylkill River Pennsylvania

The Upper Ferry bridge built at Fairmount near Philadelphia in 1812 and tragically destroyed by fire in 1838 was the longest single-trussed wooden arch in the United States, spanning over 340 feet (102 meters). It caused a sensation in its day and was inevitably labeled a new “wonder of the world,” “the Colossus at Philadelphia,” and “the Colossus at Fairmount.” This covered bridge, responding to new constraints, took timber engineering to its limits.

At the beginning of the nineteenth century, driven by the need for agricultural growth, the population of the narrow coastal plain of the northeastern United States was spreading beyond the “tidewater” region. Before then, many short streams and estuaries had adequately met communication needs, but the inland farmers demanded roads, fords, and bridges. Water mills, increasing in number as farming increased, were of necessity sited where rivers could not be forded, and they also needed transportation routes. There were good supplies of building lumber in the region and the harsh climate was better suited to wooden construction than to masonry. The earliest bridges were merely logs carried on timber stringers; their spans were limited to the available lengths. As bridge technology developed, longer spans were achieved by joining stringers and employing trusses and arches. Climate was an important factor and the covered bridge soon became not only popular but also necessary. The roof protected the structural timber from alternate wetting and drying, discouraging rot and extending the life of the bridge. There is a story, perhaps apocryphal, of a Virginia builder who observed that bridges were covered “for the same reason that our belles [wear] hoop skirts and crinolines: to protect the structural beauty that is seldom seen, but nevertheless appreciated”—a delightful analogy.
The first covered bridge in the United States replaced a pontoon across the Schuylkill River in Philadelphia and was therefore optimistically called the Permanent Bridge. A stone bridge was originally intended, but when the abutments and piers were completed in 1804, the decision was made to span the river with timber. The New England bridge architect Thomas Palmer designed a structure braced with three arches and multiple king posts, and it was constructed by Owen Biddle, a Philadelphia architect and builder. When it was opened to traffic in 1805 it had no cover, but on Palmer's advice and the prompting of Permanent Bridge Company shareholders, a roof and clapboard siding were soon added. Palmer believed the covering would extend the life of the structure from twelve years to perhaps forty; it was still sound when replaced forty-five years later.
Within five years there was a demand for another bridge across the Schuylkill, to be built at Upper Ferry and connecting the area then known as Fairmont with the western bank. The design was put in the hands of Lewis Wernwag, an immigrant carpenter from Württemburg, Germany, who had already built bridges over Neshaminy and Frankford Creeks.

Wernwag’s new bridge, built in 1812, was an elegant single-trussed arch spanning over 340 feet (102 meters)—certainly the longest of its kind in the United States and (according to some sources) the second-longest single-span bridge in the world at the time. The totally enclosed, elegant, low-arch bridge terminated in classical loggias at each end. Ten rectangular windows on each side provided light and ventilation for travelers. Graceful as it was, its achievement does not lie in its appearance but in the genius of its timber engineering. The wooden road deck was supported on five laminated arch beams that rose a little over 3 feet (1.07 meters) at midspan. On each side of the deck the river was spanned by a bow lattice beam, shallower at midpoint than at the ends and stiffened along its length with twenty-eight sets of double diagonal bracing. Iron tension ties anchored the beams to the ground at the masonry abutments, and others complemented the bracing along their entire length.

Wernwag’s reputation was established as a builder of long-span wooden truss bridges, and he built several more, including the Hickman Covered Bridge (1838) in central Kentucky. Also known locally as the Wernwag Bridge, it was the longest cantilever wooden bridge in the country. The practice of building wooden covered bridges spread quickly throughout the United States, and literally thousands were built during the nineteenth century. The Covered Bridge Society of America identifies over 1,500 extant covered bridges throughout the world. Over two-thirds of them are in North America. Pennsylvania has 219, over half of which are still in use on public roads.

Further reading

Allen, Richard Sanders. 1983. Covered Bridges of the Northeast. New York: Viking Penguin.

McKee, Brian J. 1997. Historic American Covered Bridges. New York: Oxford University Press

Colosseum (Flavian Amphitheater) Rome

The Flavian Amphitheater, now in ruins, towers over the southeast end of the Roman Forum, between the Esquiline and Palatine Hills. Its popular name, the Colosseum, was derived from the nearby colossal (120-foot-high, or 37.2-meter) bronze statue of Nero, long since vanished. The most ambitious example of a new building type associated with urbanization, the Colosseum was an architectural feat, even by Roman standards. Its size is awesome, but the logistics of moving crowds to and from their seats was also a major achievement.

The earliest amphitheater on the site was built in timber for the pontifex maximus Gaius Scribo

Curio in 59 b.c.; that; was replaced about thirty years later by a stone-and-timber version for Augustus Octavian Caesar, the first emperor. The Colosseum was commissioned in a.d. 69 by Vespasian, whose son Titus dedicated it in a.d. 80. The highest part of that structure was also timber, and not rebuilt in stone until after a.d. 223. It seems that the first three ranges of seats were completed in Vespasian’s reign, that Titus added two more ranges, and that Domitian completed the building around 300. Although early sources claim that the Colosseum seated 87,000 spectators, modern scholarship puts the figure closer to 50,000. Other Italian amphitheaters at Capua, Verona, and Tarragona are of similar size. The vast Colosseum, elliptical in plan, measured 620 by 510 feet (189 by 156 meters), covering nearly 6 acres (about 2.4 hectares). Its general height was 160 feet (49 meters).

The structural skeleton of the Colosseum was made of travertine limestone, quarried at Tivoli in the hills near Rome and transported to the site along a specially built road. Travertine blocks, some of them 5 feet high and 10 feet long (1.5 by 3 meters), were fixed together with metal cramps to form concentric elliptical walls. These were linked with radiating tufa walls carrying complex rising vaults of brick-faced concrete, in which volcanic stone such as pumice was used to reduce the weight. The vaults carried the tiers of seats. The Colosseum was built to house extravagant spectacles that took place in an arena measuring 280 by 175 feet (86 by 54 meters). Apart from a number of minor entrances to the arena, there were four principal gates at the ends of the axes, directly joined by passages to the exterior. A 15-foot-high (4.5-meter) walls probably faced with marble, defined the arena and provided a measure of protection for the spectators. The floor of the arena was made of heavy planks, strewn with sand for the purpose of soaking up the blood of gladiators, prisoners of war, and wild animals that died in their thousands. Such emperors as Caligula and Nero even ordered cinnabar and borax to replace the sand. A labyrinth of chambers beneath the floor possibly housed the participants in the games, and there were complicated machines and hoists to lift men, beasts, and theatrical sets into the arena, adding to the spectacle. Sometimes the entire floor was removed and the arena flooded by a system of pipes so that galleys could be pitted against each other in mock naval battles.
The terrace on top of the surrounding wall was wide enough to contain two or three rows of movable seats. Undoubtedly the best in the house, they were reserved for senators, magistrates, the vestal virgins, and other important people. The emperor and his immediate retinue occupied an elevated cubiculum. Upon entering the Colosseum through numbered arches corresponding to their ticket numbers, other visitors climbed sloping ramps to the gradus (bleachers), which were divided into stories and allocated according to gender and social class. The first fourteen rows of marble seats were covered with cushions and set aside for the equestrian order. Above them a horizontal space defined the second range, where a third class of spectators, the populus, was seated. Still further up were the wooden benches for the common people. The open gallery at the very top was the only part of the amphitheaters from which women were permitted to watch. There were exceptions, of course. When the games were over, the crowd could quickly disperse through no fewer than sixty-four strategically placed exits, aptly known as vomitoria.
The external wall of the Colosseum was divided into four stories, reflecting the circulation corridors within. Its eighty arches, most of which provided access to the interior, were framed by superimposed orders of pilasters (nonstructural columns): Tuscan on the ground floor, Ionic above them, and Corinthian at the top. The fourth story, also embellished with Corinthian pilasters, had stone brackets for the wooden masts from which an awning (velarium) was suspended across the interior to shield spectators from the sun while they watched the slaughter below. Many of the visible parts of the building were enriched with moldings, ornament, facings of marble or polished stone, and statuary. Fountains of scented water were provided for refreshment.
The Flavian Amphitheater was damaged several times by lightning strikes and repaired as often, so that games continued spasmodically until the sixth century, despite the opposition of the church and some Christian emperors. The last recorded slaughter of wild beasts was in the reign of Theodoric (a.d. 454–526), since when it has been used sometimes as a fortress and (to its detriment) as a quarry. Renaissance palaces in Rome, such as the Cancellaria and the Farnese, and churches including Saint Peter’s Basilica, were built with columns plundered from the ancient monument. Various popes made efforts to preserve it, and in 1750 Pope Benedict XIV consecrated it to the martyrs who died there. Surprisingly, and despite popular belief, it was not the main venue for the execution of Christians. In 1996 a U.S.$25 million restoration of the Colosseum was launched. After the cellars were drained, fallen masonry replaced, bushes and weeds cleared from the arena, and the structure repaired and cleaned, the greatest amphitheater was reopened in July 2000 with a season of Greek plays.

See also

Circus Maximus

Further reading

Luciani, Roberto. 1990. The Colosseum: Architecture, History, and Entertainment in the Flavian Amphitheatre. Novara, Italy: Istituto Geografico De Agostini.

Nardo, Don. 1998. The Roman Colosseum. San Diego: Lucent Books.

Pearson, John. 1973. Arena: The Story of the Colosseum. London: Thames and Hudson.

nius

CN (Canadian National) Tower Toronto, Canada

The CN Tower, next to the city hall on Front Street, Toronto, stands on the shore of Lake Ontario. It transmits television and FM radio for more than twenty broadcasters, as well as serving various other communications purposes. Including the masts, it is the tallest freestanding structure in the world; the top of the transmission antenna is over 1,815 feet (553 meters) high. But at the beginning of the twenty-first century, as technically demanding as it is, height alone does not constitute an architectural feat. The twin Petronas Towers in Kuala Lumpur, Malaysia, currently rank as the world’s tallest buildings, at 1,483 feet (454 meters). Others are proposed that will exceed that, including the 1,660-foot (508-meter) Taipei Financial Center on Taiwan, to be completed in August 2002, and the 2,100-foot (642-meter) Russia Tower in Moscow; at 2,755 feet (843 meters), the Millennium Tower in Tokyo will dwarf them all. The CN Tower is remarkable architecture because of its construction technique. For about a year, concrete, mixed and tested on-site to ensure consistent quality, was poured around the clock into a “slip form” that gradually decreased in diameter, to create the elegantly tapered contour of the post tensioned hollow structure.

Slip forming is a rapid construction technique based on extrusion. It employs a self-raising formwork that continually moves upward as the concrete is being placed, at a rate that gives the concrete time to set before being exposed as the formwork rises on a ring of hydraulic jacks, developing enough strength to support the work above. Continuous slip forming obviously speeds up the construction process while enabling excellent quality control, optimizing labor, and reducing the cost of building plant and scaffolding. It also results in monolithic, seamless structures. Developed in North America in the 1920s—The Granary at Logan Square in Philadelphia (1925) was one of the first examples in the United States—it has been widely used to build grain silos, building service cores, and (normally) any tall structures with a consistent cross section.
Early in the 1970s the number of multistory office blocks in downtown Toronto increased significantly, with a consequent interference with television and radio reception in large parts of the city. Toronto needed an antenna taller than any existing office block, indeed, of any that was anticipated, and the CN Tower was proposed to meet that need. The project was initiated in 1972 by the Canadian National Railway, which commissioned John Andrews Architects, working in collaboration with Webb Zerafa Menkes Housden Architects of Toronto. The structural engineering consultant was Roger R. Nicolet of Montreal; the mechanical and electrical engineers were Ellard-Wilson Associates Ltd. of Toronto; and the manager-contractor was Foundation Building Construction.
The original design proposed three concrete towers linked by structural bridges, but that was developed into a single tower with three hollow “legs.” As well as serving as electrical and mechanical service ducts, the hollow columns provided the necessary degree of flexibility for such a tall structure. Construction started in February 1973, and in four months a Y-shaped, 22-foot-thick (6.7-meter) reinforced concrete base was founded on the bedrock 50 feet (15 meters) beneath the city. The continuous slip-form process then began. When the tower reached 1,100 feet (336 meters), a seven-story “SkyPod,” fabricated on the ground, was raised into position

and anchored by twelve steel-and-timber brackets that were slowly pushed up the tower by forty-five hydraulic jacks. The concrete-walled SkyPod, reached by four high-speed, glass-fronted elevators, houses a 400-seat revolving restaurant, a nightclub, and indoor and outdoor observation decks. Later, a 2.5-inch-thick (6.4-centimeter) glass floor was installed. Beneath the SkyPod, delicate microwave dishes and other broadcasting equipment are protected by an annular radome. The concrete tower continues to the Space Deck at 1,465 feet (447 meters)—an observation gallery that on a clear day provides a view with 100-mile (160-kilometer) visibility. A Sikorsky Skycrane helicopter lifted the tower’s 335-foot (100-meter) communications mast in forty sections, each of about 7 tons (6.4 tonnes), and they were bolted together in place. The mast, erected in three weeks, was covered by fiberglass-reinforced sheathing. The maximum sway experienced at the very top in 120-mph (190-kph) winds with 200-mph (320-kph) gusts is 3.5 feet (1.07 meters).

The CN Tower was completed in June 1975 and officially opened on 1 October. It cost Can$57 million and took about 1,550 workers forty months to construct. It is nearly twice the height of the Eiffel Tower and more than three times as tall as the Washington Monument. Soaring above Toronto, it is struck by lightning about seventy-five times every year.
In 1995 Canada National passed ownership to a public company, the Canada Lands Company. In June 1998, the CN Tower officially opened a 75,000-square-foot (7,100-square-meter) expansion including an entertainment center, shopping facilities, and restaurants.

Further reading

Campi, Mario. 2000. Skyscrapers: An Architectural Type of Modern Urbansm, Boston: Birkhäuser.

McDermott, Barb, and Gail McKeown. 1999. The CN Tower. Edmonton, Canada: Reidmore Books.

Cluny Abbey Church III France

The town of Cluny in eastern France’s Burgundy region was important because of the Benedictine abbey jointly founded in 910 by Abbot St. Berno of Burgundy and William the Pious, Duke of Aquitaine. The third convent on the site, the great Basilica of St. Peter and St. Paul known as Cluny III (mainly 1088–1130), was the largest church, monastic or otherwise, in the world until St. Peter’s, Rome, was completed in the seventeenth century. Cluny III was the high point of Romanesque architecture in France, and, heralding the Gothic, it emphasized the continuity of architecture. Its form and detail repudiate the idea of a succession of discrete styles, each somehow frozen in time.

The reformist Benedictine community that originally occupied a Gallo-Roman villa in Cluny eventually developed an innovative system of centralized ecclesiastical government: by the fourteenth century the abbey controlled over 1,450 Cluniac foundations or priories from England to Poland to Palestine, which together could boast a complement of over 10,000 monks. After the pope himself, Cluny’s abbots were the most powerful clerics in the Roman Catholic Church and were at the epicenter of religious influence in Europe.
Two earlier abbey churches—the first, dedicated in 927, was succeeded by a larger building in 955–981—were replaced at the end of the eleventh century by Cluny III, which commenced soon after the other monastery buildings had been rebuilt (1077– 1085). The new church was over 440 feet (136 meters) long; the narthex and towers added in the late twelfth and thirteenth centuries brought the total length to 600 feet (180 meters). The barrel-vaulted ceiling, especially acoustically suited to the Cluniac uninterrupted sung liturgy, soared 98 feet (30 meters) above the floor. There were double transepts and double aisles to both the nave and choir; the chevet end had five chapels. The ceiling of the crossing under a central tower was 119 feet (36 meters) high. Yet Cluny III was remarkable not just for its size.
Its form, emerging over more than a century, demonstrated the perpetual development of Western

religious architecture. Since about 1000, the itinerant mason-architects of Europe had addressed their ecclesiastical clients’ demands for stone-ceiling churches (perhaps prompted by fear of fire), dealing with the major structural problems that entailed. The need to manage the huge loads and thrusts involved had led (although not all at once) to a number of architectural and engineering innovations. Cluny III, a mature expression of the new form, incorporated them all, masterfully blending liturgical and structural necessities—the two towers at the west end to provide longitudinal stiffening; vaulted aisles to brace the walls of the nave against the thrust of the stone vaults; massive side walls reinforced with even thicker buttresses, employed for a similar reason; small windows, creating the appearance of what someone called “the fortresses of God”; and a complex east end, where apsidal chapels with hemidomes completed the lucidly articulated building, which showed exactly how the vast weight of the superstructure was gently coaxed down to the supporting earth.

At the same time, Cluny III had many features that foreshadowed what would be commonplace just a few decades later: piers disguised as clusters of narrow columns, elegantly tall proportions, pointed arches (a lesson from Islam), and sophisticated vault construction. It also had beautifully carved decorations, giving a glimpse of the reemergence of naturalism. Some sources claim that here were to be found some of the first medieval sculptural allegories (dating from 1095) and the prototype for many carved and painted west portals (dating from 1109 to 1115).
Cluny III influenced a few great buildings (for example, Paray-le-Monial, La Charité-sur-Loire, and Autun Cathedral). But clergymen are notoriously conservative, and the impact of its avant-garde architecture was therefore limited. Indeed, the design was attacked in a Cistercian polemic even before the work was completed. Pope Urban II, who had been a novice and later prior at Cluny, consecrated the high altar of the unfinished church on 25 October 1095.

He announced that its community had reached “so high a stage of honor and religion that without doubt Cluny surpassed all other monasteries, even the most ancient.”

The abbey and the town both suffered in the religious wars of the sixteenth century. Early in the French Revolution the abbey was suppressed and then closed in 1790. Most of the basilica was demolished a few years later, and only ruins of the main southern transept and bell tower hint at what was once the greatest church in Christendom.

Further reading

Aubert, Marcel, and Simone Goubet. 1966. Romanesque Cathedrals and Abbeys of France. London: Vane.

Conant, Kenneth John. 1959. Carolingian and Romanesque Architecture. Harmondsworth, UK: Penguin

Clifton Suspension Bridge Bristol, England

The River Avon rises in the Cotswolds and falls about 500 feet (150 meters) in its 75-mile (120-kilometer) course to the Severn Estuary at Avonmouth. Near Bristol it passes through a channel that was cut in the nineteenth century to give access to oceangoing vessels, and then through the steep Clifton Gorge, where it is daringly crossed by the Clifton Suspension Bridge, 245 feet (75 meters) above the water. The iron structure, with a main span of 702 feet (214 meters), challenged conventional wisdom and pushed the new material and contemporary technology beyond the theoretical limits.

Bristol’s port of Avonmouth was a well-established center for coastwise and international shipping. As the nineteenth century saw accelerating growth in trade and economic prosperity, Bristol’s wealthier citizens wished to secure a market share for their city, and the renown that went with it, in the face of intense competition from such rivals as Liverpool. Perhaps they envied the prestigious bridge at (Conwy, Wales, and the Menai Suspension Bridge, both designed by the Scots engineer Thomas Telford. Funds were in hand to start the project: the Bristol wine merchant William Vick, who died in 1754, had bequeathed £1,000 to build a bridge across Clifton Gorge; the money had been accruing interest while held in trust.A design competition, announced in May 1830, attracted twenty-two entries, including four from the brilliant engineer Isambard Kingdom Brunel, who was then only twenty-four years old. The spans he proposed varied between 879 and 916 feet (267 and 279 meters); all were longer than any existing suspension bridge. The jury short-listed four designs (one of Brunel’s among them), before seeking Telford’s opinion. In an arrogant gesture he rejected all the

schemes. His given reason was pragmatic enough: his Menai bridge (1819–1826) had almost been destroyed by crosswinds; it was nearly 579 feet (175 meters) long, and Telford believed that nothing over 600 feet (184 meters) was feasible—the 700 feet across the exposed Clifton Gorge was out of the question. The committee then asked him to submit an alternative design, but the three-span bridge carried on soaring Gothic spires that he produced was unsuitable, even comical. A second competition followed in October 1830, and Telford resubmitted that design, only to see it again rejected. The twelve entries were reduced to four finalists, and Brunel’s proposal, modified so that the main span was only 630 feet (192 meters), was placed second. He went to Bristol to meet the committee and convinced them with arguments about the practicalities and the esthetic quality of his tower design. He was appointed as engineer in 1831.

Brunel had an eye for the stunning landscape, with its high wooded cliffs, and his “Egyptian” towers, although not his favorite stylistic alternative, complemented the drama of the place. He had intended to have them inscribed with hieroglyphs and crowned with sphinxes, but the cost was prohibitive. There were delays for other reasons, including the 1831 Bristol riots associated with the Reform Bill, but lack of funds was the main problem. Work did not start until 1836. More financial shortfalls caused an interruption in 1853, and the piers stood untouched for some years, even being threatened with demolition. Reusing chains from another of Brunel’s works, the demolished Hungerford Suspension Bridge (1841–1845) in London, the Clifton Suspension Bridge was finally opened in 1864, although the original design was not followed completely. Brunel had died five years earlier.

See also

Menai Suspension Bridge; Royal Albert Bridge

Further reading

Body, Geoffrey, 1976. Clifton Suspension Bridge: An Illustrated History. Wiltshire, UK: Moonraker Press.

Vaughan, Adrian. 1903. Isambard Kingdom Brunel, Engineering Knight-Errant. London: John Murray