The ground rises only slightly, forming an almost oval platform roughly 30 metres north to south and 24 metres east to west, its edge defined by a low scarp less than a metre high. A faint internal lip hints at a bank that once stood more prominently, and a shallow ditch, or fosse, still traces the outer perimeter, though just barely.

This is a rath, the Irish term for a ringfort, the most common monument type in the Irish countryside. These circular or near-circular enclosures, typically defined by one or more earthen banks and ditches, were built primarily during the early medieval period, roughly between the fifth and twelfth centuries, and served as enclosed farmsteads for families of middling status. The Castletownroche example appears on the Ordnance Survey six-inch map of 1842, drawn as a hachured circular enclosure, a standard cartographic convention for showing an earthwork in relief. By the 1935 edition of the same map series, the fosse was still being recorded. Local memory places its infilling at around 1969, a fate that befell countless similar monuments across Ireland during decades of agricultural intensification. What survives today is the scarp, the ghost of the bank, and the shallow depression of the ditch where it has not been completely levelled. A possible entrance orientation to the east-south-east is consistent with a preference seen at many ringforts across the country, where openings to the south or east were common, perhaps for reasons of shelter or solar orientation.