The hypocaust was a space under the floor where the air would be heated by a small fire. The floor was raised up by stacks of tiles called pilae, and the hot air beneath it would make it warm and ...

They were also built to strict specifications, so that their ‘hypocaust heating’ would work properly. This system used water, heated in fiery furnaces under the raised floors of the baths.

Students could equip their model with a hypocaust too, placing a floor over stacks of plastic bricks to create a cavity. The hotter the bath, the larger the hot-air cavity beneath its floor.