This 15th-century fortification stretches dramatically across the headland, its curtain wall running from the southern edge of Dun Lough to the sheer cliff face overlooking Dunlough Bay. The defensive wall, reaching heights of six metres, incorporates three towers along its length; a formidable barrier that once controlled this strategic coastal position.

The main tower, measuring roughly 8.8 by 7.4 metres, showcases sophisticated medieval engineering with its distinctive pointed arches forming the first floor ceiling, created using overlapping stone slabs. Access was carefully controlled through lintelled doorways at ground and first floor levels, with the remains of external stairs still visible at the base of the north wall. Inside, a straight mural staircase rises from the ground floor entrance to the second floor chamber, whilst another set of stairs leads from the second floor window embrasures up to the wall walk. The two smaller towers along the curtain wall feature similar construction techniques, including the characteristic overlapping slab roofs and twisting internal staircases that connected multiple floors.

Though historical records mention a castle at Dun Locha as early as 1207, the surviving structures appear to date from the 15th century when the O’Mahony clan held sway over this corner of Cork. The eastern tower, built square at approximately 4.5 metres per side, demonstrates the builders’ skill with its pointed wicker-centred vault covering the first floor and a barrel vault over the third. An arched gateway through the curtain wall once led into an entrance passage, providing controlled access to the castle’s interior. Today, these ruins offer a fascinating glimpse into the defensive architecture of medieval Ireland, where powerful families like the O’Mahonys built strongholds capable of withstanding both Atlantic storms and human adversaries.