The enclosure at Ballynabrocky is modest in scale, roughly seven and a half metres in diameter, with a stone wall less than a metre wide running around its perimeter. What makes it quietly compelling is how little of it remains visible. The blanket bog, a thick, spongy accumulation of peat that builds up over centuries in wet upland conditions, has crept over the stonework and folded it into the hillside, so that the structure reads more as a subtle disturbance in the ground than a deliberate construction.

Where the stones do break through, they appear to form a crude inner and outer facing, the technique of setting two parallel lines of upright or laid stones with a rubble core between them, which is associated with a range of enclosures from the prehistoric period onward. The wall sits on a natural terrace, a reasonably level shelf of ground on an otherwise sloping hillside, suggesting whoever built it chose the site with some care, seeking out a flat footing on difficult terrain. What the enclosure was used for is not recorded. Circular stone enclosures of this kind in upland areas are sometimes interpreted as small farmsteads, animal pens, or ritual sites, though without excavation or datable material, any single explanation would be guesswork. The bog that hides it has likely also preserved it, keeping the lower courses of stonework intact beneath a layer of peat that has been accumulating for a very long time.