This tower house, which reaches five and a half storeys despite its ruined state, commands sweeping views across the surrounding rocky landscape. Though only its northeastern and northwestern walls survive to any significant height, towering about 14 metres, they showcase the fine craftsmanship of their medieval builders, with regular stone blocks carefully laid in courses and bonded with gravelly mortar.

The castle’s history reads like a chronicle of Ireland’s colonial struggles. Known as Carrownagoul Castle in historical documents, it belonged to Dermot O’Brien in 1574, but the property changed hands repeatedly during the following century. After Mahon O’Brien’s rebellion and death in 1588, English tenants leased the castle, though the O’Briens reclaimed it by 1598. The pattern of confiscation and restoration continued through the 1641 rebellion and Cromwellian period; the castle may have been demolished on Cromwell’s orders, which would explain its current ruined state. By 1677, the O’Brien family had regained the Carrownagoul lands, though the castle itself appears to have been abandoned by then.

The architectural details that remain reveal a sophisticated defensive structure. The ground floor once featured vaulted chambers, whilst upper floors contain various loops and embrasures; some with distinctive ogee heads, others flat or round headed; positioned strategically for defence. A garderobe shaft runs through multiple floors along the northwestern wall, and remnants of a spiral staircase can still be seen in the corner. The fourth floor features an unusual architectural element: stone corbels connected by cut stone lintels that would have supported a stone wallplate. Traces of a bawn wall northeast of the tower suggest the castle once had an enclosed courtyard of approximately 1,000 square metres, completing what would have been an imposing fortification in its prime.