Ancient Roman

Roman builders combined Greek columns with the round arch, the vault (an arched ceiling) and concrete made from lime, volcanic ash and broken stone. Concrete could be cast in curved shapes, which made possible domes and halls far wider than Greek stone beams could span. Walls of concrete or brick were faced with stone, marble or plaster. The Greek orders were often applied as decoration: half-columns and pilasters (flat columns) frame the arches but carry little load.

The Pantheon in Rome, dedicated about 126 CE, has a concrete dome 43.3 m across with a 9 m opening, the oculus, at the top; it is still the largest unreinforced concrete dome in the world. The Colosseum (70-80 CE) stacks three arcades framed by Doric, Ionic and Corinthian half-columns. The Pont du Gard in southern France (1st century CE) carried an aqueduct to Nîmes on three tiers of arches 48.8 m above the river.

Early Roman temples followed Etruscan models, set on a high platform with a deep columned porch at the front, and Rome took the column orders from the Greeks. Roman concrete was in widespread use from about 150 BCE. Between about 30 and 20 BCE the architect and engineer Vitruvius wrote De architectura, ten books on building dedicated to Augustus. It is the only treatise on architecture to survive from antiquity.

Building reached its largest scale in the 1st and 2nd centuries CE, with the Colosseum, Trajan's Forum and Hadrian's Pantheon in Rome, and aqueducts, baths and amphitheaters across the provinces. The Baths of Caracalla (212-216) and the Basilica of Maxentius (completed about 312) carried vaulted construction into the 3rd and 4th centuries. In 609 the Pantheon became a church, which helped preserve it. In 1416 the Florentine scholar Poggio Bracciolini found a manuscript of Vitruvius at the Abbey of Saint Gall in Switzerland, and its first printed edition appeared in 1486, giving Renaissance architects a written guide to Roman building.