This tower house, though poorly preserved today, tells a fascinating story of medieval Irish nobility. Built by Conchur O’Sullivan, a figure who lived before 1450, the castle belonged to a branch of the O’Sullivan clan known as the Sliocht Mac Crath. The O’Sullivans were once powerful lords in this part of Kerry, and this fortress served as one of their strategic strongholds overlooking the bay.

What remains of Cappanacush today is primarily its south wall, standing almost to its original height alongside partial east and west walls. The structure rises from a large rocky outcrop on a low ridge, its limestone walls built from roughly coursed split stone bound with heavy gravel mortar that contains marine shell inclusions; a testament to local building materials. Archaeological examination reveals this was once an impressive five storey tower house, with vaulted ceilings on the first and third floors. The surviving architecture shows sophisticated defensive features typical of 15th century Irish tower houses, including narrow loops (arrow slits) set in broad embrasures, drawbar channels for securing wooden shutters, and the remnants of what appears to have been a garderobe chute in the southeast corner.

Despite centuries of decay and ivy growth, careful observation reveals the castle’s former domestic arrangements. Each floor had its own distinct features: the ground level had small defensive loops, whilst upper floors boasted proper windows with moulded jambs for light. The third floor contained a large fireplace and wall cupboard, suggesting this was likely the main living chamber. The topmost level, accessed via timber floors supported on scarcements, would have led to the battlements where fragments of a single merlon and the alure (wall walk) can still be traced near the southwest corner. These ruins, though fragmentary, offer a tangible connection to the complex political landscape of medieval Kerry, when Gaelic lords like the O’Sullivans maintained their power through networks of fortified towers scattered across their territories.