This L-shaped stronghouse, built from roughly coursed limestone rubble, once rose three storeys high, though today only fragments of its northwestern section remain. The surviving walls, measuring up to a metre thick with a defensive base-batter, hint at the building’s former strength; nearby lie Clogher Castle just 300 metres to the east-southeast and Clogher Church 400 metres to the south-southeast, suggesting this was once a significant settlement area.

The castle’s ground floor was accessed through a doorway at the northern end of the northwest wall, complete with a bar slot for securing the entrance. The defensive nature of the building is evident in the narrow slit window flanked by what appear to be gun loops, allowing defenders to protect the approach whilst remaining sheltered. A two-storey garderobe tower projects from the north angle, its compact interior dimensions of roughly 1.85 by 1.55 metres accessed via a narrow segmental-arched doorway at first-floor level. The wooden floors throughout the building were supported by timber joists, now long since vanished.

Perhaps the most intriguing architectural feature is the remains of what may have been an oriel window at the eastern end of the northeast wall. This structure appears to have been corbelled out beyond the wall face at first-floor level, with the garderobe tower providing structural support on its northwestern side. Though only partial remains survive, making definitive identification difficult, such a feature would have provided both light and a commanding view of the surrounding landscape. By 1840, the Ordnance Survey Letters described Graigone as merely “a small fragment of a castle”, suggesting its decline was already well advanced by the Victorian era.