This rectangular three-storey tower house, measuring roughly 13 metres north to south and 12 metres east to west, was likely built by Rory MacNamara, son of Síoda, in the late 15th century. The castle changed hands several times over the centuries; it was held by Donal Reogh MacNamara in the 1580s, passed to the O’Briens sometime after 1626, and was recorded in the ownership of Donough O’Brien in 1688 and Henry O’Brien in 1712. By 1837, the structure was already described as being in ruins.

The tower house features impressively thick walls, nearly 2.7 metres deep, originally faced with roughly coursed, squared and dressed masonry bonded with lime mortar. Today, much of the castle shows signs of extensive stone robbing, particularly at the corners where the well-cut quoins have been removed up to the second floor level. The ground floor entrance no longer survives, and large sections of the east wall and southeast angle are missing. Despite this deterioration, fascinating architectural details remain visible throughout the structure, including narrow loops with flat heads, cusped ogee-headed windows with hollow spandrels, and the exposed remains of a garderobe chute on the western wall that once exited about 1.4 metres above ground level.

The interior reveals that both the ground and first floors were originally vaulted, though only the rubble springing remains visible on the north and south walls. The first floor apartment featured a centrally placed fireplace with cut stone surround and mantelpiece in the south wall, complete with sloping head and cut-stone skewbacks flanking the mantel. A spiral staircase once occupied the southeast corner, though much of it has been destroyed at the lower levels. Various architectural features hint at the castle’s former sophistication: drawbar sockets for securing doors, wall niches for storage or display, multiple window embrasures with segmental arches, and put-log holes indicating the presence of a mezzanine floor. The OS historic 6-inch mapping shows a weir on the river immediately west of the tower house, suggesting the MacNamaras and later the O’Briens may have controlled water resources or operated a mill in conjunction with their fortress.