The Romans adopted the external language of classical Greek architecture for their own purposes, which were so different from Greek buildings as to create a new architectural style. The two styles are often considered one body of classical architecture. Sometimes that approach is productive, and sometimes it hinders understanding by causing us to judge Roman buildings by Greek standards.
The Romans achieved originality in building very late in their existence; for the whole of the republican period, Roman architecture was a nearly exact copy of that of Greece , aside from the Etruscan contribution of the arch, and its later three-dimensional counterpart, the dome. The only two developments of any significance were the Tuscan and Composite orders; thefirst being a shortened, simplified variant on the Doric order and the Composite being a tall order with the floral decoration of the Corinthian and the scrolls of the Ionic. Innovation started in the first century B.C., with the invention of concrete, a stronger and readily available substitute for stone. Tile-covered concrete quickly supplanted marble as the primary building material and more daring buildings soon followed, with great pillars supporting broad arches and domes rather than dense lines of columns suspending flat architraves. The freedom of concrete also inspired the colonnade screen, a row of purely decorative columns in front of a load-bearing wall. In smaller-scale architecture, concrete's strength freed the floor plan from rectangular cells to a more free-flowing environment.
On return from campaigns in Greece , the general Sulla returned with what is probably the most well-known element of the early imperial period: the mosaic, a decoration of colorful chips of stone inset into cement. This tiling method took the empire by storm in the late first century and the second century and in the Roman home joined the well known mural in decorating floors, walls, and grottoes in geometric and pictorial designs. Though most would consider concrete the Roman contribution most relevant to the modern world, the Empire's style of architecture, though no longer used with any great frequency, can still be seen throughout Europe and North
America in the arches and domes of many governmental and religious buildings. The number of orders was augmented by the addition of the Tuscan and Composite.
Tuscan Order. — This order is not unlike the Doric, and is chaste and elegant. The shaft had a simple base, ornamented with one torus, and an astragal below the capital. The proportions were seven diameters in height. Its entablature, somewhat like the Ionic, consisted of plain running surfaces.
The Composite Order. — Of this there were various kinds, differing less or more either in the ornaments of the column or in the entablature. The simplest of this hybrid order was that which combines parts and pro-portions of the Doric, the Ionic, and the Tuscan.
The temples of the Romans sometimes resembled those of the Greeks, but often differed from them. The Pantheon, which is the most perfectly preserved temple of the Augustan age, is a circular building, lighted only from an aperture in the dome, and having a Corinthian portico in front. The amphitheater differed from the theater, in being a completely circular or rather elliptical building, filled on all sides with ascending seats for spectators, and leaving only the central space, called the arena, for the combatants and public shows. The Coliseum is a stupendous structure of this kind. The aqueducts were stone canals, supported on massive arcades, and conveying large streams of water for the supply of cities. The triumphal arches were commonly solid oblong structures ornamented with sculptures, and open with lofty arches for passengers below. The edifice of this kind most entire in the present day is the triumphal arch of Constantine , at Rome .
The basilica of the Romans was a hall of justice, used also as an exchange or place of meeting for merchants. It was lined on the inside with colonnades of two stories, or with two tiers of columns, one over the other. The earliest Christian churches at Rome were some-times called basilica, from their possessing an internal colonnade. The monumental pillars were towers in the shape of a column on a pedestal, bearing a statue on the summit, which was approached by a spiral staircase within. Sometimes, however, the column was solid. The thermae, or baths, were vast structures, in which multitudes of people could bathe at once. They were supplied with warm and cold water and fitted up with numerous rooms for purposes of exercise and recreation.