Baths of Caracalla (Historical Reference)

Not a working spa but the spectacular ruins of the largest ancient Roman bathing complex (216 AD), giving context to Rome's 2,000-year-old wellness culture. The Baths of Caracalla once held 1,600 bathers simultaneously across cold (frigidarium), warm (tepidarium), and hot (caldarium) pools, plus a sweat room, gymnasium, and library. Worth visiting alongside any modern Roman spa to understand the historical depth of the wellness tradition.