Not a public house, not a warehouse, but a waterhouse, a structure associated with the storage or distribution of water in the medieval or early modern urban fabric. The precise nature of such buildings varied, but they typically served as reservoirs or pumping stations supplying water to surrounding streets and households at a time when piped water as we know it was far in the future.

The evidence for this one comes from the Friends of Medieval Dublin Map, published in 1978 and referenced under grid square O 13. This collaborative cartographic effort, supported by scholarly work compiled by Bradley and King in 1987, attempted to reconstruct the built environment of medieval Dublin by gathering documentary, cartographic, and archaeological references into a single record. The waterhouse near Crocker's Bar is one such reference, preserved in the academic literature but leaving no mark whatsoever on the present streetscape. Geraldine Stout, who compiled this entry for the Irish sites record, noted simply that there is no visible surface trace. That blunt phrase says a good deal about how thoroughly Dublin's street-level past has been rebuilt, resurfaced, and erased.

For anyone curious enough to go looking, Thomas Street remains a working commercial street and there is nothing to observe at the site itself. The value here is less in what can be seen and more in the act of reading the street against what the historical record suggests once existed beneath or behind it. The Friends of Medieval Dublin Map, produced through the work of researchers and enthusiasts concerned about the pace of development affecting the old city, is itself worth tracking down through a library or archive with an interest in Dublin's urban history. Standing on the north footpath of Thomas Street near where Crocker's Bar once stood, it is possible to think about what a city's water infrastructure looked like before iron pipes and treatment works, even if the building that answered that need has left no trace above ground.