Baths of Diocletian

The Baths of Diocletian were public baths in ancient Rome. Named after emperor Diocletian and built from AD 298 to 306, they were the largest of the imperial baths. The project was originally commissioned by Maximian upon his return to Rome in the autumn of 298 and was continued after his and Diocletian's abdication under Constantius, father of Constantine.

The baths were open until c. 537, when the Ostrogoths cut off aqueducts to the city of Rome. The site houses the Basilica of Santa Maria degli Angeli e dei Martiri, built within the ruins in the 16th century, the Church of San Bernardo alle Terme, and part of the National Roman Museum.

Source: Wikipedia