baths, in architecture. Ritual bathing is traceable to ancient Egypt, to prehistoric cities of the Indus River valley, and to the early Aegean civilizations. Remains of bathing apartments dating from the Minoan period exist in the palaces at Knossos and Tiryns. The ancient Greeks devised luxurious bathing provisions, with heated water, plunges, and showers. Bathing in public facilities, or thermae, was developed by the Romans to a unique degree. Thermae, probably copied after the Greek gymnasia, had impressive interiors, with rich mosaics, rare marbles, and gilded metals. Water, brought by aqueducts, was stored in reservoirs, heated to various temperatures, and distributed by piping to the bath apartments. Certain rooms were kept heated by means of furnaces which sent hot air into lines of flues beneath floors and in the walls. There are ruins of public baths in Pompeii, and in Rome there exist extensive remains of the thermae of Titus (A.D. 80), of Caracalla (A.D. 212–35), and of Diocletian (A.D. 302).