The logic was straightforward enough: running water carried waste away without the need for manual removal. What makes this particular case quietly interesting is less the engineering instinct behind it and more the fact that it was planned at all, formally, in writing, as a civic intervention in sixteenth-century Dublin.

The historian Clarke, writing in 2002, records a reference from 1571 to a public latrine that was to be constructed over a watercourse fed by St John's mills. The mills themselves were part of the network of water-powered grain mills that operated along the waterways running through the south of the city, drawing on streams that fed into the Liffey and its tributaries. The proposal to route a latrine over such a channel was not unusual for the period; European towns had long made use of mill races and urban streams as open sewers, and Dublin was no different in that regard. What the record captures is a moment of municipal administration, somebody thought this necessary, recorded it, and sought to have it done. Whether it was actually built is not known.

The precise location has not been established, and the watercourse itself has long since been culverted or redirected beneath the streets of Dublin's south city. There is nothing to visit and nothing to see, which is, in its own way, part of the point. The record survives not as a monument but as a line in an archive, a trace of the ordinary and unglamorous business of keeping a sixteenth-century city functional. For anyone drawn to the archaeology of everyday life, the absence is as telling as any physical remain would be.