Built by the Tyrrel family around 1410, as confirmed by dendrochronological testing of an oak floor beam, the castle served as both a defensive stronghold and a symbol of Norman power in the Irish midlands. The five-storey tower, with its distinctive pointed vault over the second level, double-stepped battlements and pair of circular bartizans, represents classic medieval Irish castle architecture. A circular flanker from the original bawn, or fortified courtyard, still adjoins the tower on the southeast side, offering a glimpse of the castle’s once-formidable defensive capabilities.

The castle’s turbulent history includes a significant moment in 1597, when Richard Tyrrel and Piers Lacy ambushed and destroyed an English force led by Christopher Barnewall near the fortress. This attack was part of the Nine Years’ War, when Irish lords resisted English expansion into their territories. By the 20th century, however, the castle had fallen into ruin, standing as a derelict reminder of Ireland’s medieval past until the 1970s when restoration work began.

The restoration, completed by Laurence Ginnell in the 1980s, transformed the ruins into what is now the Tyrrellspass Castle restaurant, though a modern wing has been discretely added at the rear. Interestingly, the restoration incorporated architectural elements from other historic sites; ogival-headed lancets on the south side were brought from Syonan Castle, whilst three two-light windows came from the ruined church at Kilbeggan. The southeast end of the tower contains a tier of small rooms positioned above the entrance and the spiral staircase, maintaining much of the original medieval layout whilst adapting the space for modern use.