The site at Ballyglass sits in grassland with bogland stretching away to the north-west, and its form, a subcircular rath roughly 38 metres across, is now so worn down that identifying it requires some patience. A rath is an earthen ringfort, typically dating from the early medieval period, constructed as an enclosed farmstead for a single family or small community. The enclosing bank here survives only as a degraded earthwork running from the south-west through the north and around to the east; elsewhere the original boundary has collapsed to little more than a scarp, a low slope where the ground simply drops away.

The site has been further altered by later agricultural use. A field boundary, the kind of stone or earthen division that would have been laid out centuries after the rath fell out of use, cuts directly across the enclosing element between the east-south-east and the south-west, effectively dismantling a section of whatever remained. One detail has survived more legibly: traces of an external fosse, the shallow ditch that would originally have run around the outside of the bank to reinforce the enclosure, are still visible on the eastern side. That a fosse existed at all suggests the original structure was built with some care, even if almost nothing of that effort is now apparent above ground.