sudatorium

And of course there's no sudatorium at all.

In architecture, a sudatorium is a vaulted sweating-room (sudor, sweat) of the Roman baths or thermae.

Some thermae also featured steam baths: the sudatorium, a moist steam bath, and the laconicum, a dry steam bath much like a modern sauna.

Outside the square of the fort is the remains of the bath house (which has a rare circular sudatorium), and the levelled parade ground, which is considered to be the finest surviving example in the Western Empire.