Etruria (now Tuscany) is presumed to have been a Greek colony, and the local style, a form of debased Doric, was adopted by the first Tarquin (who was of Etruscan origin) and introduced to Rome about 610 B.C.
With the growth of the Roman Empire, and its consequent wealth and development of luxury, great impetus was given to building and the arts generally.
The orders based on the Greek originals were developed in detail and proportion, particularly in the latter respect. Whereas in the Greek Doric the height of the column varied from about four, to six and a half diameters, the Roman version became more slender, being about eight diameters in height.
The Corinthian order, perhaps, underwent the greatest change, a change that has practically remained unaltered to the present day.
The most significant development in building was the Arch and subsequent vaulting, by means of which extensive covered areas were rendered possible. The Pantheon at Rome is covered with a hemispherical vault or dome 139 feet in diameter.
[Illustration: No. 26. Section and interior elevation of Pantheon, Rome.]
The dome, which is interiorally occupied by radiating and horizontal ribs, resulting in five horizontal rows of cassons, or coffers, is really a casting in cement; and in principle is identical with the present method of building, in which concrete or cement forms a considerable part in construction.
Apart from other reasons, the Arch was necessitated by small material, which, in the case of the Lintel, could not be employed without the device of joggelled joints. In the absence of suitable material to cover spans, it became necessary to devise some means to the desired result. This was achieved by bridging the span with separate pieces of material cut to the necessary wedge form.
The Arch was first applied to such useful and necessary buildings as the Cloaca Maxima, to aqueducts, bridges, and viaducts, from which its firm construction and power of resistance were found to be applicable to buildings of many storeys.
[Illustration: No. 27. Coliseum, Rome. Section and part elevation showing arch and vault construction.]
Apart from the early employment and development of the Arch, the Romans were content to borrow their architecture from outside sources, and also were indebted to the Greeks for their ideal expressions in poetry, art, even to religion, whose gods they invested with different names.