A Roman by the name of Sergius Orata lay the first heated tiles in Rome, creating a system called Hypocaust. The floor of a room was elevated on pillars. The floor itself was made of a layer of tiles, cement and another layer of tiles. Spaces were left in the concrete, as well as in the wall. The smoke and heat from the furnace was not directed out a chimney but rather sat in an enclosed area so that it could only escape by passing beneath the floor and up the walls and out the roof. The gaps in the concrete and walls allowed the ventilated furnace to heat the walls and floor and thus the room, bath, etc.