The circular fortification measures approximately 49 metres east to west and 33 metres north to south, its defensive wall largely collapsed except for one impressive section on the southwest side. Here, the wall still rises to 2.25 metres in height, with between 26 and 33 courses of stone intact, displaying the characteristic inward lean or ‘batter’ seen in similar structures like the nearby Doon Fort.

The island itself presents a dramatic split level interior, with a cliff edge running roughly east to west that divides the site into two distinct areas; the southern section sits nearly 3 metres higher than the northern half. Archaeological evidence suggests this natural feature was incorporated into the site’s defences, with traces of a wall running along the cliff’s upper edge. A second curved wall appears to have spanned the space between the cliff base and the northern edge of the cashel, creating what would have been a complex defensive arrangement making clever use of the island’s topography.

Today, three modern structures occupy the southeastern part of the site, whilst the surrounding landscape remains much as it likely was in ancient times; barren marshland dotted with rocky outcrops and patches of heather on the elevated ground. This remote setting in Drumboghill, County Donegal, would have provided both natural defence and isolation for the cashel’s inhabitants, who could monitor approaches across the water whilst remaining protected by their stone walls and the lake itself.