In the center, there is an uncovered pool and the toilets are aligned along the walls. The columns surrounding the pool supported a wooden ceiling. There was a drainage system under the toilets.
Public toilets in the ancient city of Ephesus
Almost every Roman city had large public latrines, where many people – often 20 or more – could relieve themselves in remarkably opulent settings.
This video by toldinstone explores how the use, decoration, and (many) hazards of Rome’s latrines.
“Ostia public toilet,” which shows a well-preserved public latrine in Ostia’s Forum Baths
Reconstruction drawing of public Latrine at Forum Hadriani, Aurelium Cananefatium/Forum Hadriani, Germania Inferior, Netherlands
Reconstruction drawing showing the original arrangement of the Latrine, Barracks, Isca Augusta
A line of timber seats was set over the drain, and in front was a gutter for the soldiers to wash the sponges which served them for lavatory paper.
Reconstruction drawing showing the communal latrines in use, Housesteads Roman Fort (Vercovicium)