over 50,000 spectators, had retractable fabric coverings for shade, and could stage massive spectacles including huge gladiatorial contests and mock naval battles. This masterpiece of Roman architecture epitomizes Roman engineering efficiency and incorporates all three architectural orders – Doric, Ionic, and Corinthian. Less celebrated but just as important if not more so for most Roman citizens, was the five-story insula or city block, the Roman equivalent of an apartment building, which housed tens of thousands of Romans. It was during the reign of Trajan (98–117 AD) and Hadrian (117–138 AD) that the Roman Empire reached its greatest extent and that Rome itself was at the peak of its artistic glory – achieved through massive building programs of monuments, meeting houses, gardens, aqueducts, baths, palaces, pavilions, sarcophagi, and temples. The Roman use of the arch, the use of concrete building methods, the use of the dome all permitted construction of vaulted ceilings and enabled the building of these public spaces and complexes, including the palaces, public baths and basilicas of the "Golden Age" of the empire. Outstanding examples of dome construction include the Pantheon, the Baths of Diocletian, and the Baths of Caracalla. The Pantheon (dedicated to all the planetary gods) is the best preserved temple of ancient times with an intact ceiling featuring an open "eye" in the center. The height of the ceiling exactly equals the interior radius of the building, creating a hemispherical enclosure. These grand buildings later served as inspirational models for architects of the Italian Renaissance, such as Brunelleschi. By the age of Constantine (306-337 AD), the last great building programs in Rome took place, including the erection of the Arch of Constantine built near the Colosseum, which recycled some stone work from the forum nearby, to produce an eclectic mix of styles. Roman aqueducts, also based on the arch, were commonplace in the empire and essential transporters of water to large urban areas. Their standing masonry remains are especially impressive, such as the Pont du Gard (featuring three tiers of arches) and the aqueduct of Segovia, serving as mute testimony to their quality of their design and construction. See also Art collection in ancient Rome Bacchic art Byzantine art Erotic art in Pompeii and Herculaneum Latin literature Music of ancient Rome Neoclassicism Parthian art Pompeian Styles Roman graffiti References Citations Sources Beckwith, John. Early Christian and Byzantine Art. Harmondsworth: Penguin, 1970. Boardman, John, The Oxford