Sudatorium

In architecture, a sudatorium is a vaulted sweating-room (sudor, sweat) of the Roman baths or thermae. The Roman architectural writer Vitruvius (v. 2) refers to it as concamerata sudatio.

In order to obtain the great heat required, the whole wall was lined with vertical terra-cotta flue pipes of rectangular section, placed side by side, through which hot air and smoke from the suspensura passed to an exit in the roof.