This formidable medieval fortification consists of a curtain wall that stretches across the entire headland, rising up to six metres in height and incorporating three towers along its length. The main tower, measuring approximately 8.8 metres north to south and 7.4 metres east to west, features an ingenious architectural detail: its first floor is supported by two pointed arches separated by overlapping stone slabs, a construction technique that demonstrates the sophisticated engineering skills of its builders.

The defensive wall runs from the sheer cliff edge on Dunlough Bay’s northern shore, connecting the three towers in a strategic line that controlled access to this remote headland. Each tower served a specific defensive purpose, with the narrow tower projecting 2.2 metres from the curtain wall’s outer face, whilst a square tower to the east measures 4.7 metres on each side. These structures feature various architectural elements typical of late medieval Irish tower houses, including spiral staircases tucked into the walls, pointed wicker-centred vaults, and barrel vaults covering the upper floors. An arched gateway through the curtain wall provided the main entrance, leading through a passage that gave controlled access to the defended area within.

Whilst the Annals record a date of 1207 for the construction of ‘Dun Locha castle’, the surviving remains appear to date from the 15th century, suggesting either a complete rebuild or that the earlier reference was to a different structure on the site. The castle was a stronghold of the O’Mahony clan, one of the prominent Gaelic families who controlled this part of southwest Cork during the medieval period. Today, the western side of the lake still shows evidence of a revetted stone wall, which may represent a continuation of these impressive defensive works, testament to the strategic importance of this windswept promontory at Ireland’s southwestern extremity.