This unusual enclosure at Carnagarve went unnoticed by Ordnance Survey mapmakers for centuries, only revealing itself through modern aerial photography before being properly surveyed by the Bernician Studies Group in 2015. From this elevated position, the site commands spectacular views along the entire length of Lough Foyle and across its narrow mouth; a location clearly chosen for its strategic advantage over both the waterway and the fertile lowlands below.

The hillfort consists of two roughly concentric banks that arc from southwest to north-northeast, set about 15 to 20 metres apart. These low, rounded earthworks, now marked by bands of thicker heather growth, appear to represent only the northwestern half of what may have been a circular or oval enclosure. The inner bank stretches approximately 70 metres and would have enclosed a summit area of perhaps 70 to 80 metres across, whilst the outer bank curves in a deeper semicircle spanning about 130 metres. Both banks disappear into an impenetrable thicket of gorse and brambles on the steep southwestern slope, making it impossible to determine whether they once completed a full circuit or relied on the hill's natural defences; its eastern and southeastern sides drop away sharply, providing protection without the need for artificial fortification.

Several intriguing features dot the interior space, including a circular hollow measuring 5 to 7 metres across and various smaller depressions near the western section of the inner bank, though these are now engulfed in gorse and their original purpose remains unclear. A gap in both banks on the northwestern side may mark an original entrance, aligned to provide access whilst maintaining the site's defensive advantages. The compact, firm nature of the banks and the possible presence of fosses (defensive ditches) suggested by the soft, wet ground outside them hint at considerable engineering effort, though time and vegetation have obscured many details of the original construction.