That fragment is easy to miss, jutting out from a modern field boundary on a south-facing slope of pasture, yet it is the last trace of a rath, the Irish term for a ringfort, a type of enclosed farmstead built in earthen banks and ditches that was the standard unit of rural settlement across Ireland during the early medieval period, roughly between the fifth and twelfth centuries.

The 1842 Ordnance Survey six-inch map recorded the site clearly, depicting a hachured circular enclosure sitting at the junction of three fields. Hachuring, the use of short radiating lines to suggest raised ground, was the standard cartographic method of marking earthworks at the time, and its presence here confirms the rath was still recognisable as a coherent feature in the mid-nineteenth century. At some point after that survey, the enclosure was levelled, and a field boundary was cut through it on a north-north-west to south-south-east axis, bisecting whatever remained. A note compiled by James Grove White between 1905 and 1925 records an observation from the Ordnance Survey Office in Dublin that Clenor South also contained a second fort nearby, described simply as small and large, though nothing further was noted beyond that brief mention.