Competed by the Emperor Caracalla in AD 217, it was a grand recreation area for Romans until the 6th century when the plumbing was cut by invading Goths.

The bath could accommodate over 1500 people at once. A Roman bath took a while, beginning with a hot bath, then a trip to the calidarium, a kind of sauna/steam room. Next you moved to the tepidarium, a warm room, and then the frigidarium, a cool room (pictured). Finally, the bather would jump into the natatio, a swimming pool (to the left of the picture).

This picture was taken from one of the two gymnasiums, the other is at the far end of the frigidarium through the arched doorway. The baths also included a library, conference rooms, and a 3000 seat stadium.