The site at Roo presents as an almost square walled enclosure, roughly 53 metres on its longer axis, which is slightly unusual; most Irish ringforts tend toward a circular or oval plan, so the near-square geometry here is one of the details that makes it worth pausing over.

The enclosure may be a cashel, the term used for a ringfort built from dry-stone walling rather than an earthen bank, which was the more typical construction method across much of Ireland. It may alternatively be a moher, a class of enclosure discussed by Elizabeth FitzPatrick and associated with specific land-use and territorial functions in the medieval period. Within the interior, satellite imagery shows a roughly rectangular structure in the southern half, measuring around eight metres by five, as well as what appear to be internal divisions or later animal pens in the north-western and south-eastern corners. Those later pens are a common enough sight inside old enclosures; once the original function of a ringfort was forgotten or abandoned, the ready-made stone walls made convenient shelters for livestock. The site was identified and reported by Jean-Charles Caillère, working from Google Earth imagery dating to March 2015.