A ringfort, or rath, is an early medieval enclosure typically defined by one or more earthen banks and ditches, used as a defended farmstead. This one is unusually substantial: a circular area roughly 32 metres across, enclosed by two earthen banks separated by a fosse, which is the ditch running between them. The outer bank extends further outward to the south-west, creating a raised platform about five metres wide between itself and the inner fosse. A break in the outer bank to the south-west suggests an original entrance. Both banks are heavily overgrown, and the interior similarly so, giving the whole structure a smothered, half-submerged quality that makes its scale easy to underestimate from a distance.

What gives this particular ringfort an added layer of historical interest is that a medieval castle once stood within it. Writing in 1750, the historian Charles Smith recorded that a castle belonging to the Barrys had been built inside an ancient fortification near Castlecor House. The Barrys were one of the great Anglo-Norman families of Cork, and it was not uncommon for such families to reuse pre-existing earthworks when establishing a stronghold, the older banks offering ready-made defensive advantage. By 1934, when local historian Bowman returned to the question and identified Smith's "ancient fortification" with this ringfort specifically, no physical trace of the castle remained above ground. The rath had outlasted the structure built inside it, though whether the castle stones were robbed out for building material elsewhere, as so often happened, the record does not say.