A natatorium (plural: natatoriums or natatoria, also called swimming hall) is a building or room containing a swimming pool.
The word natatorium was borrowed from Late Latin, transitioning around the 1880s. The word was originally constructed from the Latin for "to swim" (natā(re)) and "place" (tōrium).
In Latin, a cella natatoria was a swimming pool in its own building, although it is sometimes also used to refer to any indoor pool even if not housed in a dedicated building (e.g., a pool in a school or a fitness club).
A natatorium will usually also house locker rooms, and perhaps allied activities, such as a diving well or facilities for water polo. Many colleges, universities, and high schools have natatoriums.