A ringfort, or rath, is a circular enclosure typically defined by one or more earthen banks and ditches, built during the early medieval period as a farmstead or place of status. The one at Coolcloher has been levelled almost entirely, but a faint rise in the pasture still traces its outline, and a field fence curves away to the south-west in a slight arc, as if the farmer who set it down had decided, without much fuss, to work around something older than the field itself.

The site appears clearly on the Ordnance Survey six-inch map of 1842, drawn as a hachured circular enclosure roughly 28 metres across. By the time the 1904 and 1937 editions were produced, only the western half was being indicated, suggesting that even cartographers had noticed the gradual disappearance of the eastern portion. A 1934 record by Bowman, who measured the structure at approximately 32 yards in diameter on what was then D. Guerin's land, noted that about half of the circuit still stood to a height of around three feet. That earthwork is now gone, but an aerial photograph has captured what the eye on the ground cannot easily read: a cropmark outlining the circular bank, the differential growth of grass above buried soil betraying the shape of the original enclosure with surprising clarity.