Built from greywacke, limestone blocks and rubble, this three-storey structure reveals a fascinating approach to medieval building techniques; the angle towers and barrel vault were erected as free-standing structures first, with the connecting walls filled in afterwards rather than being bonded together. The most striking architectural feature is the barrel vault that covers only the northern half of the ground floor, its arch clearly visible on the exterior faces of the side walls, whilst the southern portion was originally roofed with timber.

The castle's defensive capabilities are evident in its tower arrangement, though not all were equally functional. The southeast tower houses the spiral staircase that provides access to all levels, whilst the northwest tower contains garderobes at the second and third storeys, complete with elaborate seating constructed from greywacke slabs. Curiously, the southwest tower's ground floor was never intended for use, having no openings or access points. The first floor served as the main living area, featuring a central fireplace in the north wall and a large window with seating built into its embrasure on the west side. Small details like cubby-holes in the walls, beam holes indicating a wooden loft, and the remains of various windows and doorways paint a picture of daily medieval life within these walls.

Entry to the castle is through a doorway in the west wall, positioned just north of the southwest tower, which leads directly to the stairwell in the southeast tower. The construction throughout shows a mix of practical and defensive considerations; relieving arches near the tops of the east and west walls support the wall-walk above, whilst numerous slit openings with rough greywacke jambs provided both light and defensive positions. The northeast tower, remarkably small and key-shaped in plan at just over a metre across, appears to have served purely defensive purposes. Though ivy has obscured some upper portions and time has taken its toll on the wooden floors that once divided the southern sections, the castle remains an impressive example of medieval Irish fortification, documented in historical surveys dating back to Wright's 1758 illustrations.