The feature is penannular, meaning it forms an almost complete ring left open at one point, with a diameter of roughly 82 metres north to south. The bank itself is modest now, rising only about ten centimetres above the interior ground level and around sixty centimetres on the outer face, but local memory holds that it was once considerably higher. A fosse, or external ditch, once accompanied the eastern side, adding a further layer of enclosure to what is already a structure of some ambition in its original scale.

Early twentieth-century Ordnance Survey maps recorded the earthwork clearly, showing the arc with hachuring that indicated a scarp running from the north-northeast around to the south, and the 1936 edition captured the eastern fosse before it had further degraded. What the enclosure was actually built for remains an open question. The place-name Kilbolane is suggestive; the kil element derives from the Irish cill, meaning a church or early ecclesiastical cell, and local tradition has connected the site with either a church foundation or a burial ground. Neither has been confirmed by excavation, and the earthwork could equally represent a secular enclosure of the kind used for settlement or livestock management in early medieval Ireland. The ambiguity is part of what makes it interesting: a large, carefully constructed ring in the landscape whose original meaning has slipped away.