The Roman public latrine is one of the few structures from antiquity that still makes modern visitors physically uncomfortable. A long stone bench, twenty or more keyhole-shaped openings cut into it at close intervals, no partitions, no doors, and a shallow water channel running along the floor at the feet of everyone seated. It looks less like a bathroom than like a piece of civic furniture — which is precisely what it was.

Rome’s reputation for hydraulic sophistication rests almost entirely on what came in. The aqueducts are celebrated, documented, still standing in fragments across three continents. What went out receives less attention — which is itself a Roman attitude, one the city encoded in both its architecture and its social hierarchy. The removal of waste was essential, constant, and largely invisible, performed by people the Latin sources named only when something went wrong.