A ringfort, or rath, is a roughly circular earthwork enclosure dating typically from the early medieval period, used as a farmstead and defended by one or more banks and ditches. At Ruanes, that enclosure has been levelled by agriculture, leaving no visible trace for anyone walking the field today. And yet two pieces of iron slag have been recovered from the soil, small fragments that hint at metalworking activity within or near the fort, and aerial photography has revealed the buried bank as a cropmark, the differential growth of crops above buried features that allows archaeologists to read the landscape from the air in ways invisible at ground level.

Ordnance Survey mapping traces the site's gradual disappearance. On the 1842 six-inch map it appears as a hachured circular enclosure of around 20 metres in diameter. By the 1905 and 1936 editions, the depicted diameter had grown to roughly 38 metres and a surrounding fosse, or ditch, was clearly indicated, suggesting either that surveyors were recording the feature more fully or that earlier maps had simply captured the inner element. The most detailed human account comes from Bowman, writing in 1934, who recorded a single-ramparted fort of approximately 46 yards in diameter on land belonging to a D. Aherne. Bowman noted that the bank still stood around four feet high and the fosse reached about five feet deep, with the interior saucer-shaped and sitting roughly two feet above the level of the surrounding field. That raised, bowl-like interior is characteristic of many Irish raths, the result of centuries of accumulated occupation material. Within a few decades of Bowman's visit, the earthwork had been ploughed flat.