One of them, according to local knowledge passed down with the land, opens into a chamber. The enclosure above ground is a rath, the Irish term for a roughly circular earthen ringfort, a type of farmstead enclosure built in early medieval Ireland, typically between the sixth and tenth centuries. Most survive as little more than a raised rim in a field. This one carries an extra detail that most do not.

The visible remains at Ballinorig are modest enough: a circular area of about thirty-three metres in diameter, enclosed by a low earthen bank that rises only half a metre above the exterior ground level and sits just under half a metre above the interior. The bank is four metres wide at the top, which is substantial for something so flattened by time and agriculture. Beneath or within the enclosure, the land was reported to contain a souterrain, an underground stone-lined passage or chamber commonly associated with ringforts and used variously for storage, refuge, or both. What distinguishes this particular one is the reported presence of two oak doors inside it, one of which led into a separate chamber. Oak used in underground structures can survive for extraordinary lengths of time in the right conditions, and the detail of fitted doors suggests a souterrain of some deliberate construction rather than a simple passage. The overall outline of the monument, now largely levelled, remains faintly legible from aerial imagery.