A fish palace sounds grand, even ceremonial, but the reality was rather more industrial: in early modern Ireland and Britain, a fish palace was a shore-based facility for processing and curing fish, typically pilchard, before the catch was packed and exported. What remains at Ballynaule, on the narrow isthmus east of Crookhaven in west Cork, is a single substantial wall, built in coursed rubble and running roughly northeast to southwest for about eight and a half metres. At its highest it still stands to 3.3 metres, with a thickness of 0.7 metres. It sits along the south side of a road, in pasture, and gives little away.

The association with a fish palace comes from the work of Arthur Ernest William Went, who referenced this site in a 1946 publication on the Irish pilchard fishery. Pilchard processing was a significant industry along the south-west Irish coast during the sixteenth and seventeenth centuries, largely driven by demand from Catholic markets in southern Europe, particularly Spain and France, where salted and pressed pilchard was a staple during fast days. A fish palace in this context would have included pressing houses, salting cellars, and storage for the hogshead barrels in which the cured fish and their extracted oil were shipped. The Crookhaven area, with its sheltered natural harbour and proximity to the open Atlantic pilchard grounds, was well placed for such an operation. Whether this particular wall formed part of a pressing house, a store, or some enclosing structure is not certain, but its solid construction and remaining height suggest it was built to last and to work hard.