By 1654, when surveyors documented it during the Civil Survey, they found ‘The ruined Castle of Glanehelty ye walls standinge’, suggesting the structure had already fallen into disrepair following the turbulent years of the Confederate Wars. What remains today is a fascinating architectural puzzle, where medieval defensive architecture has been absorbed into later domestic buildings.

The original tower house, constructed from limestone with carefully dressed corner stones, once stood three or four storeys tall but has since been reduced to just two levels. The rectangular structure measures approximately 8.8 metres north to south and 10.5 metres east to west, with walls 1.4 metres thick; substantial enough to withstand siege warfare. A pronounced base batter, rising 3.45 metres and projecting 0.4 metres at its base, provided additional structural support and defence against undermining. The original entrance, a pointed Gothic doorway with an external rebate for securing heavy doors, can still be traced on the eastern side, though much of the building’s original character has been obscured by later modifications and a rendered exterior finish.

Inside, the castle tells a story of adaptation and reuse. The ground floor, which once served defensive purposes, was transformed into a Victorian parlour by the nineteenth century. A spiral staircase tucked into the southeast corner, now blocked between ground and first floor, once provided access to the upper levels. On the first floor, pairs of limestone corbels projecting from the eastern and western walls mark where wooden floor joists once supported an upper storey. Though much altered, with its western face completely remodelled and original windows replaced, Glenahilty Castle remains a tangible link to medieval Ireland, when such fortified residences dotted the landscape, serving as both homes and strongholds for the Anglo-Norman and Gaelic nobility.