The castle’s main structure consists of a square bawn measuring 30 metres across, with walls 2.2 metres thick, originally defended by circular towers at its southeast and southwest corners. Though only foundations remain of the southeast tower, an 18th-century sketch by Hooper shows it once stood four storeys tall, complete with cross-loops for defence and a chimney rising above its parapet. The castle’s builders employed an interesting architectural feature; a series of relieving arches at the base of the north and east walls, similar to those found at Ormond Castle, which helped distribute the weight of the massive stone walls above.

The southwest tower remains remarkably intact, rising three storeys and displaying some rather sophisticated medieval comforts. Each floor features carefully designed defensive windows, with the ground floor sporting large cross-loops with stirrup bases set into embrasures that still show traces of their original plank-centring. The upper floors weren’t just about defence though; they included fireplaces, wall cupboards, and multiple garderobe chambers accessed through narrow mural passages. The tower’s entrance, rather cleverly, opens at first-floor level through a narrow passage within the wall’s thickness, meaning defenders originally used a wooden ladder to reach the ground floor, making unauthorised access considerably more difficult.

The castle’s northern wall once housed the main residential buildings, including a rectangular tower house at the northeast corner, a hall in the centre, and another building with a circular tower at the northwest angle. Evidence suggests there was also an outer bawn extending westward, connected to the main structure by a thin wall and defended by an additional circular tower that still stands today, though it’s now largely covered in ivy and inaccessible. The pronounced base-batter along the riverside walls, reaching three metres in height and 0.4 metres in width, provided extra stability and defence against both river erosion and potential attackers, while the more modest batter on the landward sides suggests the builders knew exactly where their greatest threats lay.