The enduring nature of the Classical system, which is almost entirely based on the principles of masonry construction, may again serve to underline the fact that until the last two hundred years builders could rely only on naturally-occurring materials to construct durable shelters. (Concrete, requiring the sourcing, preparation and admixture of such specialised materials as ash and quicklime, may be a partial exception.) Here the list of serviceable substances is a short one: earth (tamped, mixed with water, dried or baked), sand (for foundations), stone, wood, and – more rarely – animal parts (bone, leather) and various organic materials that are susceptible to weaving (reeds, twigs, bark). Wood has the advantage of being both relatively easy to process into framing units and relatively sturdy, though it is always vulnerable to rot, fire and insects; few ancient buildings using timber construction survive today. As the following pages will confirm, it is stone, because of its durability and great compressive strength, which has remained the material of choice for monumental buildings over many thousands of years. (And it might even be argued that concrete, which has supplanted stone in almost all modern constructions, presents itself simply as a more liquid, and hence more easily malleable, form of stone.) The most conservative method of masonry construction, as in a conventional load-bearing wall or the Egyptian pyramids, is simply to lay brick on brick or stone on stone; this can be done to some height before the foundations are crushed by the increasing weight. If the building is of multiple stories, however, this simple technique tends to demand extremely thick walls with small openings, allows little or no scope for useable internal space, and is wasteful of materials and labour. The driving technical question through much of architectural history has therefore been: how can we come up with a structural method that will allow a stone building to have both larger openings and spacious interiors? The greatest liability of stone is its heaviness and brittleness, and much ingenuity has been spent trying to find methods to get stone to span greater and greater distances without the danger of collapse. Likely drawing on now-vanished timber prototypes, one early solution was trabeation, the structural basis of Classical architecture: in conjunction with solid wall construction for the inner sanctuary, Greek temples relied almost exclusively on a simple post-and-beam method. The greatest danger here is in proposing bays of excessive length; i.e., leaving too much space between upright supports, which risks cracking the horizontal members that are made to span them. In large rooms, the low tensile strength of stone necessitates the use of either a grid of vertical supports (posts or piers) to hold up the ceiling, or a lighter timber superstructure, though the latter will again be subject to fire or other hazards. Preferentially, therefore, roofs and ceilings were often to be built using masonry, and various methods of vaulting were developed. An early technique, known as corbelling, simply extends each successive layer of stone slightly beyond the one below until a ceiling of tapered section is formed. The true arch, making use of a semicircle of voussoirs (individual blocks of trapezoidal form) and secured on top by a keystone, was much used by the Romans in both honorific and utilitarian contexts. The extension of an arch in a single direction in space results in a semicircular barrel vault (a half-cylinder), while its rotation through 360 degrees creates a hemispherical dome. Such forms provided the best method of vaulting into the early medieval period, though they often required the use of lighter materials (usually brick) and heavy buttressing in order to counteract the lateral thrust that was thrown onto the external walls. It remained for the master masons of the Gothic period to perfect a more daring and effective form of stone vaulting, one which took the material to the limits of functionality. Making use of a pointed arch for both arcades and interlacing rib vaults, as well as a series of flying buttresses to provide lateral stability, the Gothic builders were able to realise elegantly skeletal constructions that made minimal use of load-bearing wall construction and soared to unprecedented heights.
The story of architectural technique from the late 18th century through the present day is largely one of the increasing mastery of metallic construction. Following the innovations of the Industrial Revolution, first iron and then steel were pressed into use for utilitarian structures: warehouses, factories, stores and other commercial buildings could be erected quickly and cheaply, using cast-iron elements for internal framing and external cladding. Increasingly, iron framing also began to be used for larger public buildings, notably the new Houses of Parliament in London, but these were inevitably clad in a veneer of stone or terracotta to gave the impression of traditional load-bearing construction, thus catering to genteel notions of how architecture was supposed to look. This was also true of the early skyscrapers of Chicago and New York, whose façades did not begin to make clear formal acknowledgement of their internal steel frame construction for some decades. Later in the 19th century the first experiments began to be made with reinforced concrete, which optimally combined the tensile strength of iron or steel rebar with the compressive strength of concrete. At the same time, the development of such new building technologies introduced a vexing split into architectural practise: the field of engineering was now emerging as a specialised discipline in its own right, and techniques and aesthetics thus became estranged. A telling comparison might be made between two prominent buildings erected in Paris after the mid-19th century: Charles Garnier’s new Opera house (1861–1875) and the Eiffel Tower (1889). The Opera, designed by an academically trained architect, epitomised the French belief that Paris was the centre of world culture, and that its major opera house should exemplify the grandest formal design and the most sophisticated and allusive veneer of sculptural and painted ornamentation, both inside and out. Stylistically, the Opera synthesises over two thousand years of Classical architecture, drawing on the formal vocabulary of the Greeks and Romans as filtered through the Renaissance and Baroque, and thus presented itself as a summation, if not an apotheosis, of the European cultural tradition. The Eiffel Tower, on the other hand, designed as a temporary structure for a world fair, had aims that were technical and commercial rather than strictly cultural in nature, namely: reaching an unprecedented height, minimising weight and wind resistance, and making a dramatic demonstration of the new techniques of iron construction that had been developed by French engineers. Obeisance to historical precedent or accepted canons of taste played no part in this venture, and upon its erection the tower was roundly condemned as a brutal monstrosity by a coalition of prominent French artists and writers. The question seemed clear: was architecture to be a matter of good design in the humanistic tradition, or was it instead to be a technologically-driven search for scale, economy and efficiency?
It was left to the ideologists of the Modern movement in the early 20th century to attempt to forge a reconciliation between art, architecture and industry. The key ingredient, as it turned out, was modern painting and sculpture, which provided architects with a new language of abstract form and space creation that seemed suited both to the Fordian and Taylorian exigencies of modern industry and to the increasingly collective (i.e., anti-individualistic) nature of contemporary society. This is not to say that modern architecture was conceived as simply cheap, functional, expedient or anonymous, but rather that it evinced a carefully considered ‘machine aesthetic’ that was seen to be in tune with the modernist Zeitgeist of mass production, standardisation and collectivism. At the same time, modern architects made great inroads into the creative deployment of newer materials – notably glass, steel and reinforced concrete – to fashion envelopes and spaces of compelling beauty and originality. In the work of contemporary modernists like Norman Foster or Santiago Calatrava, the line between technology and art has been completely