Underfloor heating system in Villa Romana del Casale, Sicily
Remains of the Roman floor heating system – hypocaustum – in the Roman Villa Romana del Casale in Sicily. The floor rested on visible brick pillars (pilae) about 80 cm high, and in the visible space warm air, which was generated by heating in the furnace, was supported. The system was expensive and required constant servicing of slaves; therefore only richer citizens could afford it.