Baths of Caracalla

Emperor Caracalla opened them in AD 216, and they worked for about three centuries, until the Goths cut the aqueducts in 537. They could take some 6,000 people a day, with cold, warm and hot pools, gyms, gardens and two libraries.

Walls more than 30 metres high survive, along with large stretches of floor mosaics. Underground are the tunnels where slaves kept the furnaces going. In summer, the Rome Opera stages open-air performances among the ruins.