While local historians Killanin and Duignan attribute the castle’s origins to the De Vesci family in the 13th century, with later expansions by the 6th Earl of Kildare in 1420, no visible traces of the original medieval structure remain. What survives today is the northwest half of what was once a three-storey rectangular tower house, measuring approximately 8.5 metres from northeast to southwest.

The castle has suffered dramatic collapses over the years, with the most recent major loss occurring in 1984 when the southeast half of the structure fell. An earlier collapse in 1896 proved equally devastating; contemporary accounts describe how the eastern corner gave way during heavy rains, destroying the original entrance with its murder hole, much of the internal staircase built into the wall thickness, and several upper chambers. Today, visitors can still make out key architectural features in the remaining walls, which stand about 1.5 metres thick and are constructed from rubble masonry without the typical defensive battering found in many Irish castles.

Despite its ruined state, the surviving portions reveal the castle’s sophisticated design. The ground floor preserves an intramural staircase in the northeast wall with a small chamber beneath, whilst the northwest wall features a wide fireplace arch. The first floor, indicated by joist holes in the walls, once contained a spiral staircase in the north angle, a garderobe chamber with defensive loop in the west angle, and a single light window; remnants of a partially robbed bartizan can still be traced on the western corner. A similar layout was repeated on the second floor, with a vault springing from the northwest wall to roof this level. The castle also holds a place in local folklore, being associated with the Ballad of Oonah More, adding a layer of cultural significance to these weathered stones.