Dome

Octagonal hall of the exedra, formerly the Planetarium (begun 1928); Diocletian’s largest single project in Rome was the great baths that bear his name on the Viminal Hill (ca. AD 298-ca. 306). Their layout owes much to the Baths of Caracalla, although they are even larger in scale. The central bathing block is a building of considerable complexity with its changing rooms, open-air swimming pool, bathing halls, hot and cold pools, palaestrae (exercise grounds) and warren of service corridors and furnace rooms. Many of the rooms have been preserved because various parts later were converted to ecclesiastical or other use. Parts of the frigidarium were transformed by Michelangelo into the church of S Maria degli Angeli (1566), with the result that some of the original spatial and lighting effects of the interior can still be appreciated. The church of San Bernardo alle Terme uses one of two circular rooms and the main hall and octagonal aula are parts of museums. Source: Grove Art Online; http://www.oxfordartonline.com/ (accessed 7/29/2012)