Built probably in the second half of the 1500s, this granite fortress belonged to Nicholas Devereux, who owned 240 acres across Coolhull and nearby St. Imoge’s parish by 1640. The house passed to the Earl of Anglesey during the Cromwellian period and appears to have been abandoned sometime before 1839, when Ordnance Survey maps still showed it as a roofed structure.

The castle’s design reveals the transitional nature of Irish fortified houses during this period, combining residential comfort with serious defensive capabilities. The rectangular three-storey main house connects to a four-storey entrance tower, slightly offset to create better defensive angles. Every detail speaks to security concerns: the pointed doorway protected by both a machicolation above and a yett (iron grille gate), the anti-clockwise newel staircase that disadvantaged right-handed attackers, and the sophisticated system of pistol loops and shot-holes throughout. The first floor served as the main living area, evidenced by two fireplaces suggesting division into separate rooms, whilst the ground floor provided storage and the upper floors likely contained private chambers.

What makes Coolhull particularly fascinating is its state of preservation; the stepped crenellations remain intact, and even the corner machicolation at the northeast angle survives complete with its defensive loops. The tower contains a hidden chamber or oubliette beneath the garderobe, accessible through a floor opening, whilst the parapets retain their original three-step merlons. Recent archaeological investigations have uncovered medieval pottery in the surrounding topsoil and traces of an old drainage system connected to the garderobe outlet, though no evidence of an outer bawn wall has been found. Now protected as a National Monument, Coolhull Castle offers an unusually complete picture of how the Anglo-Irish gentry fortified their homes during Ireland’s turbulent late medieval period.