The older structure, a prehistoric stone cairn roughly six metres across and no more than sixty centimetres at its highest, has been slowly losing its shape for centuries. It sits low and broad, its stones partly swallowed by sod, the whole thing slumped in the way that cairns do when the hands that built them are long gone and the hill has had time to reclaim what it can.

A cairn of this type is essentially a mounded heap of stones, often raised over a burial or used as a territorial or ritual marker, and this one crowns the highest point of the hills with what would have been deliberate intention. A single possible kerb stone survives on the southern edge, a flat-set stone about a metre long that may once have formed part of a defining ring around the cairn's base, though no comparable stones are visible anywhere else along the circuit. Whatever order originally gave this structure its outline has mostly dissolved into the hillside. On top of all of this, at some point in the more recent past, a second and much smaller pile of stones was added, two metres wide and a metre tall, serving as an Ordnance Survey trigonometrical point. These trig points were placed across Ireland and Britain to allow precise land surveying, and whoever positioned this one would have chosen the summit for the same reason the cairn's builders did: the elevation commands long views, particularly out towards the coastline.