A ringfort, or rath, is an enclosed farmstead of early medieval Ireland, typically a circular area of ground bounded by one or more earthen banks with accompanying ditches, known as fosses. This one at Kilnacloona still has its outer bank standing to a reasonable 1.9 metres on the western side, and a faint trace of the fosse survives, but the eastern arc has been worn almost flat. The interior, measuring roughly 38 by 34 metres, slopes gently downhill toward the east, and the whole site looks out from a north-facing slope over the river below.

What makes this particular rath quietly melancholy is what the 1842 Ordnance Survey six-inch map records versus what exists today. When that survey was carried out, the enclosure appeared circular and reasonably intact. By later editions, it was already being mapped as semi-circular, the eastern side evidently diminishing over time. The greater loss, however, came more recently. According to local information, a second outer bank, standing to around a metre in height, and the intervening fosse between the two banks, which reached a depth of approximately three metres, were removed around 1978 to 1979. Multi-vallate ringforts, those with more than one enclosing bank, are generally considered to have been higher-status sites in early medieval Ireland, and the removal of that second circuit, however routine it may have seemed at the time as a matter of land clearance, erased one of the features that distinguished this site from more ordinary examples. There is now no visible surface trace of that outer bank or its fosse whatsoever.