Castlestuke, as it’s known locally, occupies an extraordinary position atop a natural sea stack rising some four metres above the surrounding landscape. Historical records from 1601 mention the castle was inhabited by the son of Phelemy Brasleigh O’Doherty, a prominent figure in the region’s tumultuous history. Local tradition, documented by Shaw-Mason in 1814, tells a rather touching story; the castle was supposedly built by O’Doherty as a refuge to protect his children from smallpox outbreaks that periodically ravaged the Irish countryside.

The physical remains tell their own story of this unusual fortification. The summit of the stack measures roughly seven by four metres, barely enough space for a modest structure. At its centre lies a subrectangular depression, approximately 1.5 by 2.5 metres and half a metre deep, likely marking where the main tower or keep once stood. Visitors today can still spot courses of masonry clinging to the northwestern edge of the stack, stubborn survivors of four centuries of Atlantic storms and coastal erosion.

Not far from Castlestuke, near Lagacurry, another unclassified castle site adds to the area’s medieval landscape. While less dramatically positioned than its stack-top neighbour, this second fortification serves as a reminder of how densely fortified County Donegal once was, particularly during the volatile period when Gaelic lords like the O’Dohertys maintained their power through a network of strongholds. Together, these sites offer a glimpse into a time when even the most precarious locations were pressed into service for defence, whether against military threats or, as folklore suggests, the invisible enemy of disease.