Sources/Further Reading:.
Wiederholt, Kirstin. Baths & Bathing as an Ancient Roman. https://depts.washington.edu/hrome/, 2004.
https://www.pbs.org/wgbh/nova/lostempires/roman/day
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Hypocaust ruins showing the pillars which supported the floor and the remains of the floor. The arch at the rear held the furnace,
ANCIENT ROMAN BATHS · Torch: U.S. · Summer 2021
After the apodyterium came the main bathing rooms: the tepidarium, caldarium, and frigidarium, famously distinguished by their water and room temperatures. The tepidarium was a comfortable room temperature, and shaving and massages also took place here. In contrast, the steamy caldarium was heated by a hypocaust, a furnace-like system depicted below. As a result, temperatures typically surpassed 100ºF (about 38º for Celsius enthusiasts), and the high humidity would make the room feel even hotter! After the caldarium came the frigidarium, where the Romans would cool off and relax. The Romans also believed that the vast differences in temperature would help their skin care routines, as their pores opened in the heat and closed again in the cold.
Diagram of a hypocaust, which was a furnace which heated the baths from beneath the floor.
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