A drumlin is one of those smooth, elongated hills shaped by glacial activity, and in Ulster they occur in their hundreds, rolling across the landscape in what local tradition calls the "basket of eggs" country. This particular hilltop, in the townland of Cordevlis, carries on its summit a raised, roughly circular enclosure of grass and scrub, its form preserved well enough that the original geometry is still legible from the ground.

The enclosure measures approximately 34 metres on its longer axis and 30 metres across, defined by an earthen bank that, on its exterior northern face, still rises to around two and a quarter metres. This is the kind of earthwork archaeologists classify as a ringfort, a form of enclosed settlement that was built and used across Ireland primarily during the early medieval period, roughly the fifth to twelfth centuries. Most were the farmsteads of farmers and local landowners, enclosed for the protection of livestock as much as for any military purpose. What gives the Cordevlis example a certain character is the survival of its outer fosse, a defensive ditch, which remains most legible on the south-south-west to north-east arc. Beyond that ditch, an outer field bank can be traced running from the south-west to the north-north-west. The original entrance, about two and three quarter metres wide at its base, faces east-south-east, a common orientation for ringforts, though here there is no surviving causeway that would once have bridged the ditch and given access across it. A farm lane now skirts the southern edge of the fosse, which gives a sense of how these features became quietly absorbed into the working agricultural landscape over centuries, their boundaries repurposed rather than erased.