This O’Loughlin stronghold, first recorded as ‘Nacapaghee’ in 1574, occupies a dramatic setting: a steep ridge rises to the west, whilst the land tumbles away into a gully to the north, and a narrow strip of pasture stretches eastward, bounded by a low ridge. The castle changed hands several times over the centuries, occasionally falling under O’Brien control, before being forfeited to John Blake and John Morgan after the 1641 rebellion. The Cromwellian commissioners likely ordered its demolition, reducing what was once a formidable five storey towerhouse to the ruins visible today.

The surviving structure reveals the bones of a modest but well built fortification, measuring 6.5 metres long by 5.5 metres wide, with walls reaching up to 14 metres high in places. Constructed from regular limestone blocks set on a narrow plinth of cut stone and quarried bedrock, the castle shows sophisticated defensive features despite its compact size. The north wall remains the most intact, preserving arrow loops on the first and second floors, including an angled loop for covering blind spots, and stone vaulted ceilings over the ground and second floors. Among the collapsed rubble of the west wall, remnants of a stairwell and garderobe shaft can still be identified, whilst fragments of windows and doors peek through the stonework elsewhere.

When the antiquarian George Macnamara photographed the castle around 1900, three walls still stood tall and three floor vaults remained intact; today’s ruins tell a story of continued decay. Traces of the original bawn wall, the defensive courtyard enclosure, survive to the east, north and west of the tower. Rather poignantly, pieces of the castle live on elsewhere: two loop heads and a window sill have been recycled into the wall of a small shed near a farmhouse about 400 metres to the north, ensuring that fragments of this medieval fortress continue to serve the local community, albeit in a rather more humble capacity.