The Diocletian Baths in Rome are a huge thermal complex housed a central building with calidarium, tepidarium and natatio (rooms for hot or warm baths and swimming pools filled with cold water, partly preserved) disposed along the short axis, and gymnasiums on both sides of the long axis, with a large court all around used as garden.
Inside the complex there were open exedras (perhaps used for conference rooms and public readings), wide rectangular rooms (libraries) and circular rooms at the west and south corners, transformed later into the church of S. Bernardo alle Terme and into a restaurant with an arena
Today's Piazza della Repubblica traces the line of the large exedra of the Baths,in front of which there were calidarium, tepidarium and " basilica " transformed later by Michelangelo (1563-66) into the church of S. Maria degli Angeli.
Redesigned by Vanvitelli (1749), it is the church used for official religious services. Noteworthy mostly for its huge proportions, and for its eight colossal monolithic columns in red granite (13.80mt. high), belonging originally to the Baths. The name "Termini", given to the central railway station, reminds deformed, the memory of the "terme"(baths).
Some of the nearby hotels to the Diocletian Baths which work with Rome Hotels Direct are the Quirinale Hotel and a recent addition in 2010 the Opera Hotel in Via Nazionale. There is a super square in front of the baths which MUST be seen both at daytime and at night when the central fountain is illuminated making it one of the most beautiful squares in Rome.