In architecture the meeting of Greece and Italy produced a vigorous new tradition. Among its products were new types of building:
the well-to-do Roman town-house combining Italic atrium with Hellenistic peristyle (below, pp. 718 ff.); the aisled basilica, an
administrative building evidently descended from the Greek stoa; and the Roman temple. The latter inherited Italian features,
notably a high podium and a strong frontal emphasis (much more pronounced than in the east); there was normally no access save by
a monumental stairway leading up to the facade. But the decorative detail, and especially the use of Corinthian columns, was
imported from the Greek world; and, once the Italian quarries at Luni had been opened in the third quarter of the last century B.C.,
marble became the standard building material, as it had been (where possible) in Greek temples. The last step of significance in the
evolution of the temple was the creation of the fully fledged Corinthian entablature, complete with modillions on the underside of
the cornice; this had happened by the time of the Second Triumvirate and should perhaps be credited to the unknown architect of the
temple of Venus Genetrix in Julius Caesar's Forum.
But more important than purely formal changes was the emergence in Italy of a new technique: concrete construction. This began to
appear in the late third century and perhaps resulted from experimentation with pise (rammed clay) building of the type previously
used in Punic Africa; at all events it rapidly developed once architects discovered the remarkable cohesive strength and hydraulic
properties of mortar made with the central-Italian volcanic earth known as 'pulvis puteolanus' (pozzolana). Concrete replaced ashlar
as the logical medium for vault-construction. Not only did it enable buildings to be put up more economically, since materials were
cheaper and the bulk of the work could be carried out by mass unskilled labour (readily available in the form of slaves and prisoners
of war), but the results were also stronger and more adaptable: a well-built concrete vault, once set, is monolithic and can be used to
roof much larger spaces than any form of stone construction. The new technique ultimately enabled the Romans to develop their
great imperial edifices of mass circulation: the amphitheatres and public baths.
Porticus Aemilia In Rome (193 BC). The reconstruction shows how the gigantic warehouse consisted of a series of vaulted bays
connected by transversal archways. It is the earliest surviving large-scale example of concrete vaulted architecture in the Roman
world. The new technique provided greater floor-space, allowed better illumination, and reduced the risk of fire.