Built by Caracalla between 212 and 217 AD, they are still well preserved. The thermal baths, that had a capacity of more than 1500 people, were restored by Aureliano, Diocleziano and Teodorico. They stopped to work after 537 following the siege of Rome on behalf of the leader of the Goths, Vitige who broke the aqueducts in order to stop the supply of water to the city.They present a plant similar to the Thermal Baths of Traiano. On the two sides of the central body there are a series of rooms placed in a specular way, divided by the rooms arranged on the central axis, constituted by the calidarium, the hot water tub, the tepidarium, a basilican room and the big cold water pool (natatio) with which the baths ended. The entrance was close to the pool, then the people went to the dressing room (apodyterium) and then to a big gymnasium that was connected to various rooms with tubs. Then, the calidarium was reached, a large circular room that had a cupola roof ; the big windows let the sun warm the temperature from morning to sunset. In the centre there must have been a circular tub while smaller ones were between the pillars that held the cupola. It was possible to follow the same itinerary up to the hot water tub coming from the opposite side of the building, which was exactly identical.The underground of the thermal baths is very interesting, there are many rooms where all the services were taken care of in order to have everything function perfectly, in one of these rooms a mitreo was installed, the biggest one in Rome. During the excavation, since the XVI century, many works of art were found, like the three famous sculptures "farnesiane" (the bull, the flora, and Hercules) which are now in the National Museum in Naples and the two big granite pool which are now in Piazza Farnese in Rome.