Pl.: alvei

A hot-water pool, mainly found in the heated rooms of Roman-style baths. Most of these pools could accommodate several people at a time. The hot water was supplied by a boiler in the service rooms, mounted above the furnace of the hypocaust. It was kept warm by means of the hypocaust running under the pool and/or by means of a testudo. Alternatively, the alveus was heated only by an underlying furnace or by the hypocaust and wall heating. See also solium.

One of the alvei of the caldarium of the Forum Baths of Ostia (room H on this plan). Note the two small square openings in the back wall, presumably for the water supply to the pool, and the larger one underneath for the furnace and a testudo alvei (photo Allison Smith).