The Baths of Caracalla (Thermae Antoniniani) were built south of the Caelian Hill, which was the most south-easterly of the seven hills of Rome. The Caelian is described as a tongue "2 kilometres long and 400 to 500 metres wide" in A Topographical Dictionary of Ancient Rome. The Servian Wall included the western half of the Caelian in the city of Rome. During the Republic, the Caelian was densely populated. After a fire in A.D. 27, the Caelian became home to Rome's wealthy.