Roman underfloor heating system (hypocaust)

Timeline

1. 1–100Rome · LazioLarge public baths of the early empire commonly used hypocaust systems, with air heated in fire chambers conducted through terracotta pillars to the floors of warm and hot bath halls; sites such as the Baths of Caracalla preserve complete underground structures.
2. 100–200Pompeii · CampaniaVillas of the wealthy and military barracks introduced underfloor heating; smaller hypocaust installations were found at sites in Pompeii, Britain, and along the Rhine frontier, meeting the needs of colder climates.
3. 200–300Britain · Roman imperial provincesUnderfloor heating spread with Roman bath culture into Gaul, Britain, and North Africa; sites such as the Baths at Bath show local craftsmen mastering standards for brick pillar construction and flue design.
4. 300–400Constantinople · ByzantinePalaces and baths of the Eastern Roman Empire in the late empire continued the hypocaust tradition; palace ruins in Constantinople show the technology was still used in elite buildings in the 4th century, later influencing Byzantine bath architecture.