Aqueducts fed thousands of gallons of water into the system of baths and steam pipes beneath the floor heated the water. The plan is symmetrical --the Romans liked symmetry-- with separate areas for men and women. At the center of the structure were the baths proper: a "frigidarium" (cold bath), several "tepidaria" (warm baths), and a "caldarium" (steam bath). Usually bathers went through the sequence in that order.