Terme di Caracalla
Opened around 216 AD, the Baths of Caracalla were less a place to wash than a vast leisure complex — capable of holding some 1,600 bathers at once, with hot, warm and cold halls, an open-air swimming pool, gymnasia, libraries in Greek and Latin, gardens and shops. The towering brick walls that survive give only a skeletal sense of the original, which was sheathed in coloured marble, mosaics and colossal statues (the famous Farnese Hercules and Farnese Bull were dug out of these ruins).