The early architecture of Rome,--locally occupying a position between the Greek colonies to the south and the Etruscan cities to the north,--partook, as it would seem probable, of the characteristics of both, and was more especially marked by the union of the Greek orders and their trabeated structure with the arched construction shadowed forth by the buildings of Etruria. The whole history of Roman architecture seems to evince a competition ever going on between these rival systems. It was at first an unequal contest, for the arcuated system had never, when first taken up by the Romans, had the advantage of being treated as the vehicle for architectural decoration--it was as yet _mere construction_; while the trabeated system had passed through a refining process of two thousand years’ duration, and had been brought by the Greeks to the highest pitch of beauty and perfection. The Roman structures display every step in this contest, some of their greatest structures being purely arcuated and merely constructive, others as purely trabeated--mere imitations of Grecian architecture; but the majority uniting both in different proportions, the Grecian element being very commonly little more than a decorative overlaying of the arched reality. As time moved on, the arched construction steadily gained ground: not only were openings arched over, but wide spaces vaulted both with domes, continuous cylindrical vaults, and those of the groined or intersecting form. During the later ages of Pagan Rome, though architecture as a decorative art was on the wane, the triumph of arched construction became more and more complete. Columns hitherto used to support horizontal entablatures were employed directly to carry arches, the architrave being bent into a semicircle instead of lying horizontally upon the column; while spaces of gigantic span were covered with groined vaulting, some reaching to a width never since attempted. In the Eastern empire the dome became subsequently the favourite form of vault, though, in each division of the empire, the arching over entire buildings in all its branches was practised with the greatest skill and success.