Roman and early Christian
Rome before the Etruscan advent was a small conglomeration of villages. It was under the new masters that, according to tradition, the first public works such as the walls of the Capitoline Hill and the Cloaca Maxima were constructed. Considerable evidence of the Etruscan period in Rome’s history has come to light in the region of the Capitol. That there were rich tombs in Rome itself cannot be doubted—they were probably similar to those found in the Latin town of Praeneste. Meanwhile, by the beginning of the 6th century bce the Etruscans had included Fiesole and Volterra in their northern limits and at the same time began to push southward into Campania. Capua became the chief Etruscan settlement in this region and Nola a second; a necropolis has been found in the Salerno region and Etruscan objects in low levels at Herculaneum and Pompeii. The coastal region was still, however, in Greek hands.
William CulicanRepublic and empire
Roman architecture was almost as complex as the Roman Empire itself; it was influenced by a multitude of geographic, climatic, political, economic, social, and cultural factors. The cohesive factor through all the differences, the Roman people possessed the talent and felt the necessity to organize in large and complex terms—politically, architecturally, or otherwise.
Modern knowledge of Roman architecture derives primarily from extant remains scattered throughout the area of the empire. Some are well preserved, and others are known only in fragments and by theoretical restoration. Another source of information is a vast store of records, including dedicatory and other inscriptions on public works. Especially important is a book on architecture by the architect Vitruvius, who lived about the time of Christ. His book De architectura (c. 27 bce; “On Architecture”) is a handbook for Roman architects and covers almost every aspect of architecture, but it is limited because it was based on Greek models and was written at the beginning of a more creative phase of Roman architecture, in the period of the empire.
Building materials
The material employed in the earliest buildings constructed around Rome was tuff, a volcanic rock of varying hardnesses, some soft enough to be worked with bronze tools. Later, other harder volcanic stones were used, such as peperino and albani stone from the nearby Alban hills. Under the later republic and the empire the most important stone for building was travertine, a limestone quarried mainly at Tivoli. An example of the use of travertine is the exterior of the Colosseum in Rome. The use made by the Romans of marble was mainly decorative. It was set in cement and applied in slabs to brick and concrete walls. It was used for pavements either in slabs cut and arranged in patterns or as mosaic. Under the empire a great demand arose for coloured marbles and such stones as porphyry, granite, and alabaster, which were imported from various parts of the empire. The abundant use of these marbles is well illustrated by the remains of the Flavian palace on the Palatine Hill in Rome and of Hadrian’s Villa at Tivoli.
Unburned bricks faced with stucco were used especially for private houses during the republic. Of these, naturally, very few remain. Under the empire, kiln-baked bricks and tiles were the most common facing for concrete. They were never used to build a whole wall in the modern manner but merely as a protective skin. These bricks or tiles were almost always used in triangular shapes. Large tiles about two feet square called bipedales were also employed.
The use of stucco over unbaked brick and over coarse stone was prevalent from the earliest times in Greece, Sicily, and Italy. It served as a protection against the weather and also as a finish. Later it was used over brick and concrete. It was often made of lime, sand, and fine marble dust, and some forms would take a high polish or fine molding. Thus, it became the usual ground for decoration especially in the interiors of houses, examples of which abound at Pompeii and Rome. Bronze was another material primarily used in a decorative manner; doors, grilles, panels of ceilings, and other details were made of it.
For their concrete the Romans used pozzolana, a fine, chocolate-red volcanic earth, which when mixed with hydrated lime forms an excellent cement that will set well even under water; there are extensive beds of the substance at Pozzuoli, near Naples, and around Rome. With this cement was mixed an aggregate of broken tuff, travertine, brick, or even marble, with pumice stone being used in vaults after the 1st century ce to lighten the weight of the structure. Concrete was used in all great imperial buildings (for example, in the Pantheon, Baths of Caracalla, and Basilica of Maxentius in Rome). New forms of architecture that were developed by the use of this material spread throughout the Roman Empire, although in the provinces other, often weaker, kinds of concrete were used.