Romans loved to paddle from tepidariums to caldariums, then to frigidariums, and the remains of the Baths of Diocletian that you can see today give some idea of the size of these baths, which could accomodate up to 3,000 customers simultaneously. Today, the site is taken over by the church of Santa Maria degli Angeli and part of the National Roman Museum, particularly the octagonal room (or planetarium).