Above is an image of a typical Roman bath plan.
Rooms IX, X, XI, XIII, and XIV were tepidarium and calidarium rooms. These rooms were heated by hypocausts which were small areas located under the floor. Fires were kept burning in the hypocausts to heat the floors and water in these rooms. Rooms III, IV, and V were frigidaria, or cold rooms. Rooms I and II were changing rooms. Room VI was the center of the bath complex and featured a large mosaic. Rooms VII and VIII were probably meeting rooms were people sat around and talked. Room XII was the entrance to the baths.