Terme di Caracalla

Lonely Planet review

Rome's most awe-inspiring ruins, the Terme di Caracalla are a striking reminder of the massive scale on which Rome was built. Spread over 10 hectares, the ancient leisure centre could hold up to 1600 people and included caldaria (hot rooms), a lukewarm tepidarium, a swimming pool, gymnasiums, libraries, shops and gardens. Between 6000 and 8000 people were thought to have used them every day.

While the free citizens splashed around in the pools, hundreds of slaves sweated in the 9.5km (5.9mi) of underground tunnels, tending to the complex plumbing systems. Begun by Antonius Caracalla and inaugurated in 217, the baths were used until 537 when the grubby Visigoths smashed their way into Rome. Excavations in the 16th and 17th centuries unearthed important sculptures, many of which found their way into the Farnese family collection. Two enormous basins, for example, now serve as twin fountains in Piazza Farnese.

Opera fans should note that spectacular outdoor performances are staged here in summer.