The earliest inhabitants of Rome were an Aryan or, as they used to be called, Indo-Germanic race, who established themselves in a country previously occupied by Pelasgians. Their principal neighbour on one side was Etruria, a Pelasgian nation. On the other hand was Magna Græcia, which had been colonised in very early ages by Hellenic settlers of kindred origin. It was therefore impossible that the architecture of the Romans should not be in fact a mixture of the styles of these two people. As a transition order, it was only a mechanical juxtaposition of both styles, the real fusion taking place many long centuries afterwards. Throughout the Roman period the two styles remain distinct, and there is no great difficulty in referring almost every feature in Roman architecture to its origin.
From the Greeks were borrowed the rectangular peristylar temple, with its columns and horizontal architraves, though they seldom if ever used it in its perfect purity, the cella of the Greek temples not being sufficiently large for their purposes. The principal Etruscan temples, as we have already shown, were square in plan, and the inner half occupied by one or more cells, to the sides and back of which the portico never extended. The Roman rectangular temple is a mixture of these two: it is generally, like the Greek examples, longer than its breadth, but the colonnade never seems to have entirely surrounded the building. Sometimes it extends to the two sides as well as the front, but more generally the cella occupies the whole of the inner part though frequently ornamented by a false peristyle of three-quarter columns attached to its walls.
Besides this, the Romans borrowed from the Etruscans or Greeks a circular form of temple. As applied by the Romans it was generally encircled by a peristyle of columns, though it is not clear that the Etruscans so used it; this may therefore be an improvement adopted from the Greeks on an Etruscan form. In early times these circular temples were dedicated to Vesta, Cybele, or some god or goddess either unknown or not generally worshipped by the Aryan races; but in later times this distinction was lost sight of.
A more important characteristic which the Romans borrowed from the Etruscans was the circular arch. It was known, it is true, to the Egyptians, Assyrians, and Greeks; yet none of these people, perhaps excepting the Assyrians, seem to have used it as a feature in their ornamental architecture; but the Etruscans appear to have had a peculiar predilection for it, and from them the Romans adopted it boldly, and introduced it into almost all their buildings. It was not at first used in temples of Grecian form, nor even in their peristylar circular ones. In the civil buildings of the Romans it was a universal feature, but was generally placed in juxtaposition with the Grecian orders. In the Colosseum, for instance, the whole construction is arched; but a useless network of ill-designed and ill-arranged Grecian columns, with their entablatures, is spread over the whole. This is a curious instance of the mixture of the two styles, and as such is very characteristic of Roman art; but in an artistic point of view the place of these columns would have been far better supplied by buttresses or panels, or some expedient more correctly constructive.
After having thoroughly familiarised themselves with the forms of the arch as an architectural feature, the Romans made a bold stride in advance by applying it as a vault both to the circular and rectangular forms of buildings. The most perfect examples of this are the rotunda of the Pantheon and the basilica of Maxentius, commonly called the Temple of Peace, strangely like each other in conception, though apparently so distant in date. In these buildings the Roman architects so completely emancipated themselves from the trammels of former styles as almost to entitle them to claim the invention of a new order of architecture. It would have required some more practice to invent details appropriate to the purpose; still these two buildings are to this hour unsurpassed for boldness of conception and just appreciation of the manner in which the new method ought to be applied. This is almost universally acknowledged so far as the interior of the Pantheon is concerned. In simple grandeur it is as yet unequalled; its faults being principally those of detail. It is not so easy, however, to form an opinion of the Temple of Peace in its present ruined state; but in so far as we can judge from what yet remains of it, in boldness and majesty of conception it must have been quite equal to the other example, though it must have required far more familiarity with the style adopted to manage its design as appropriately as the simpler dome of the Pantheon.
These two buildings may be considered as exemplifying the extent to which the Romans had progressed in the invention of a new style of architecture and the state in which they left it to their successors. It may however be worth while pointing out how, in transplanting Roman architecture to their new capital on the shores of the Bosphorus, the semi-Oriental nation seized on its own circular form, and, modifying and moulding it to its purpose, wrought out the Byzantine style; in which the dome is the great feature, almost to the total exclusion of the rectangular form with its intersecting vaults. On the other hand, the rectangular form was appropriated by the nations of the West with an equally distinct rejection of the circular and domical forms, except in those cases in which we find an Eastern people still incorporated with them. Thus in Italy both styles continued long in use, the one in baptisteries, the other in churches, but always kept distinct, as in Rome. In France they were so completely fused into each other that it requires considerable knowledge of architectural analysis to separate them again into their component parts. In England we rejected the circular form altogether, and so they did eventually in Germany, except when under French influence. Each race reclaimed its own among the spoils of Rome, and used it with the improvements it had acquired during its employment in the Imperial city.
Orders.
The first thing that strikes the student in attempting to classify the numerous examples of Roman architecture is the immense variety of purposes to which it is applied, as compared with previous styles. In Egypt architecture was applied only to temples, palaces and tombs. In Greece it was almost wholly confined to temples and theatres; and in Etruria to tombs. It is in Rome that we first feel that we have not to deal with either a Theocracy or a kingdom, but with a great people, who for the first time in the world’s history rendered architecture subservient to the myriad wants of the many-headed monster. It thus happens that in the Roman cities, in addition to temples we find basilicas, theatres and amphitheatres, baths, palaces, tombs, arches of triumph and pillars of victory, gates, bridges, and aqueducts, all equally objects of architectural skill. The best of these, in fact, are those which from previous neglect in other countries are here stamped with originality. These would have been noble works indeed had it not been that the Romans unsuccessfully applied to them those orders and details of architecture which were intended only to be applied to temples by other nations. In the time of Constantine these orders had nearly died out, and were only subordinately used for decorative purposes. In a little while they would have died out altogether, and the Roman would have become a new and complete style; but, as before remarked, this did not take place, and the most ancient orders therefore still remain an essential part of Roman art. We find the old orders predominating in the age of Augustus, and see them gradually die out as we approach that of Constantine.