That absence is itself the puzzle. Most prehistoric or early medieval enclosures of this kind, broadly referred to as forts or raths, earthwork enclosures that typically served as farmsteads or places of status, preserve at least a fosse, the surrounding ditch that helped define and defend the interior. Here, none is visible, which leaves the structure occupying an ambiguous place between monument and mystery.

The enclosure sits towards the lower end of a NNW-SSE drumlin ridge, the kind of long, smoothed hill left behind by glacial action and characteristic of the Monaghan landscape. When the Ordnance Survey mapped this area in 1834, they recorded a large circular enclosure with an external diameter of around 75 metres, a considerable size. By the time the revised edition appeared in 1907, the feature had already begun to lose its shape on paper, depicted as a D-shaped hachured outline measuring roughly 60 metres across in either direction, and noticeably cut into by field banks at its north-west and north-east edges. On the ground today, the earthwork measures approximately 64 metres north to south and 61 metres east to west. A slight but readable scarp defines it along the east, south, and west sides, best preserved at the south-west where it reaches about 1.1 metres in height and 6.1 metres in width. A field bank running north-east to south-west has clipped the north-west corner, one of the small indignities that agricultural boundaries have quietly inflicted on monuments across the Irish countryside for centuries.