That uncertainty is not a gap in the record so much as a feature of it; the building has vanished so thoroughly that even its footprint on the quayside has been lost, leaving historians with little more than a date and a direction of travel.

What the record does preserve is this: the combined City and Four Courts Marshalsea occupied a site on Bridge Street before being relocated in 1704 to the southern end of Merchant's Quay. A Marshalsea was a particular type of debtors' prison, historically associated with the court of the Marshal and used to hold those who owed money or had been taken into custody under certain legal jurisdictions. Dublin had its own version, tied to both civic and judicial authority, which is why this one carried the dual designation of City and Four Courts. The detail comes from De Courcy's 1996 study, which places the move clearly enough but offers nothing further about the building's form, scale, or eventual fate. The precise location, as the historical notes put it plainly, has not been identified.

For anyone drawn to the idea of walking the site, Merchant's Quay today is a busy stretch of the south bank of the Liffey, running westward toward the Four Courts on the opposite shore. The southern end, where the prison supposedly stood, has been built over and rebuilt across the intervening centuries, and there is nothing on the ground to indicate what once occupied the space. No plaque marks it, no outline survives. The interest here lies less in what can be seen and more in the exercise of standing somewhere that history has recorded without preserving, trying to square a documented fact with a thoroughly ordinary piece of cityscape.