Roman thermae of Sant Boi, Roman bath complex in Sant Boi de Llobregat, Spain.

The Roman thermae of Sant Boi is an ancient bath complex featuring multiple interconnected chambers that once served for washing and relaxation. The excavated site still displays the underground pipes and heating chambers that circulated warm and cold water throughout the structure.

The baths were founded around 200 CE, as revealed by restoration work begun in 1989, and remained in use until the 5th century. Their design links them to contemporary bath complexes in the Balkans and along the lower Danube, showing how ideas circulated across the Roman Empire. A 17th-century farmhouse built over the ruins helped keep the remains intact until their rediscovery in 1953.

These were private baths belonging to the family of a Roman villa, not a public social hub. Bathers undressed in the apodyterium, where slaves guarded their clothes and kept outsiders out, and wore wooden clogs to protect their feet from the heated floor.

The baths stand in the old town on Avinguda Maria Girona, at the corner of Carrer del Hospital, near the town hall, the railway station and the main museum site at Can Barraquer. A protective building erected after 1959 shelters the remains, so visits are indoors. Wooden-soled sandals were worn in the heated rooms to protect the feet from the underfloor heating.

The heating system worked through tiny channels beneath the floors that circulated warm air evenly throughout the rooms. This method allowed people to bathe comfortably even on the coldest days.