the Corinthian in particular, were adopted by the increasingly wealthy Romans. But the Romans were to transform architecture and take it beyond the range of forms that was readily available from the Hellenic world.
Though Roman architecture owed so much to the Hellenic world, its principal preoccupation was with the curve, which had been almost completely ignored by the Greeks for centuries. The traditional trabeated construction associated with Greek Classical architecture was to be gradually replaced by the arches, vaults, and domes at which the Romans came to excel. The use of the curve created an entirely new dynamic in architecture. In a Roman colonnade, for example, the viewer's eye can begin at any point on the column and has the option of going up or down and then, when it reaches the architrave, it has the option of moving left or right. Such units, arranged in a series, "proceed across space in leaps . . . conquering distances in a way that is alien to the slower and more methodical march of columns" (Kostof 193). The curve occurred at all points in Roman architectural design; in the layout of the plans, in the elevation, and, perhaps most importantly, in the containment of interior space. Vaulting and domes were really just two more ways in which the curve could be expressed.
The arch and the barrel-vault had been in use for centuries in Mesopotamia and Egypt. Domes had been employed, at least on a small scale, in the Middle East for centuries. Though they had contacts with all these civilizations, the Greeks "were seemingly not roused, even by Alexander's conquests, to any great interest in these alien methods" (Robertson 231). But the Romans, in order to exploit the curve in new ways, took rapidly to the use of concrete. The Romans did not invent concrete, as "structural adhesives of lime, sand, and water were well known" in several regions of the pre-Roman Mediterranean (MacDonald 4). The advantages of...