Roughly 40 metres by 35 metres, the enclosure sits quietly in grazing land, its edges softened by scrub growth, its original purpose unrecorded. What makes it linger in the mind is precisely that ambiguity: it is old enough to appear on the first edition Ordnance Survey six-inch map of 1839, yet no name or function was attached to it even then.

The 1839 OS mapping, Ireland's first systematic national survey conducted at that scale, captured the landscape with considerable care, noting field boundaries, earthworks, and features that local people clearly considered worth recording. At Ballynaboley, the surveyors marked not only the rectangular outline but also an external fosse, a dry or water-filled ditch, running along the eastern side. Such a fosse would have served a defensive or drainage function, and its presence suggests this was a deliberately bounded space rather than a casual agricultural arrangement. Two field boundaries are still legible in the landscape, one running north-east to south-west up to the north-western perimeter, another running north-west to south-east parallel to the eastern side, which may indicate that later farming activity here respected, or was simply constrained by, whatever earthwork already existed.