Truth and Beauty : The Basilica of Saint Mary of the Angels and Martyrs and the Baths of Diocletian

Santa Maria degli Angeli, is a unique Renaissance church in Rome. Designed by Michelangelo, it was built inside the Roman walls of the Baths of Diocletian. It is dedicated to the Virgin Mary, to the angels, and to the Christian slaves who died building the baths.

The Baths of Diocletian were the largest thermae ever built in Rome. The complex, constructed in the early third century, could accommodate an estimated three thousand people. Parts of the bath complex have survived thanks to their incorporation into newer structures. The baths were built between 298 and 306 AD by Maxentius who had the complex named Thermae Diocletiani, after Emperor Diocletian.

For Romans, bathing was a social event and the huge bathing complexes reflected their importance in Roman society. A visit to a bath complex like that of Diocletian started in the apodyterium, where visitors stored their clothes. They then progressed to the frigidarium (the cold water), the tepidarium (warm water) and the caldarium (hot water). Some visitor went to the sudatorium (sauna) before going to the caldarium. Men and women bathed separately.

But a visit to the baths was more than just about getting clean and relaxed. People came here to socialize, discuss politics, recount daily events and gossip. It was also a fitness and leisure center: there was a swimming pool, a massage room and complexes like that of the Baths of Diocletian boasted amenities such as sporting facilities, libraries and meeting halls.

The Baths of Diocletian measured 356 meters long and 316 meters wide (about 1200 x 1000 ft) and were the largest of the approximately nine hundred bath houses in Rome. The enclosed complex was structured similarly to the Baths of Trajan and Baths of Caracalla, with a central axis around which the actual baths were located. Water was led to a large water basin via the Aqua Iovia, a branch of the Aqua Marcia aqueduct.

The transept of the basilica is located in the tepidarium (luke-warm bath) of the Baths of Diocletian. It was first adapted by Michelangelo, and then altered by Lo Duca and Vanvitelli. The cross vault is 29 metres high, and the columns 17.14 metres including bases and capitals, with a diameter of 1.62 metres. Eight of the columns are from the baths, while the other eight are imitations covered with stucco. The eight large paintings that decorate the transept were originally in St. Peter's Basilica and were moved here in the 18th century. The floor was laid in the 18th century by Giuseppe Barbieri.

On the left side is the Meridian Line, a sundial laid down along the meridian that crosses through Rome, at latitude 15º. At true noon, about 12.15 pm (1.15 pm in summer time), the sun casts its light on this line. Part of the cornice on the right side of the transept wall has been cut away to provide the effect. The markings were made by the astronomer, mathematician, archaeologist, historian and philosopher Francesco Bianchini. Bianchini had been commissioned by Pope Clement XI to make them for the Holy Year of 1700. It took a bit longer; they were completed in 1703 with the assistance of the astronomer G.F. Maraldi.