Roughly four metres high and about ten metres across its longest axis, it is built primarily of stone, with earth mixed in, but the centuries have not been kind, and neither has more recent human activity. A field fence cuts straight through it, and a modern shed has been pressed up against its south-eastern face, where the ground drops away sharply by six metres. Quarrying has taken more. Whatever coherent shape the structure once held, it holds no longer.

Cairns, in the Irish prehistoric tradition, are stone-built burial monuments, often raised over chambers containing human remains, and frequently sited at prominent, elevated positions in the landscape. That pattern fits here: the location is near the highest point in the surrounding area, a placement that recurs across Irish cairns from the Neolithic and Bronze Age periods and that may have carried ritual or territorial significance for the communities that built them. But the destruction at Coolgreany has been thorough enough that even the basic question of what this structure originally was cannot now be answered with confidence. The stone core survives, the elevation survives, and the general form of a mound survives, yet the evidence that would allow a proper classification, whether burial chamber, clearance cairn, or something else entirely, has been lost to quarrying, farming, and construction.