A cairn is simply a mound of stones, often prehistoric in origin, raised as a marker or monument on high ground. This one, roughly subcircular in plan, measures about 4.7 metres across at its base and stands on average 1.2 metres tall, built from flat limestone boulders with an uneven coursing visible on its slightly battered, inward-leaning exterior. At its centre sits an Ordnance Survey trigonometric pillar, and it is quite possible that the cairn's current tidy form owes something to the OS crews who placed it there, rather than to whoever first raised the monument.

Excavation carried out in 1993 established that the cairn's lowest course rests directly on bedrock, which at least confirms that the hillfort summit itself has not been artificially built up beneath it. The hill reaches a height of 264 feet, or just over 80 metres, and the cairn commands the interior of Mooghaun hillfort, a site whose multiple enclosing ramparts make it one of the more significant later prehistoric monuments in Munster. Traces of limestone rubble around the northern and western edges of the cairn suggest that the structure was once larger, or that material has simply tumbled over time. A set of limestone-slab steps on the southern side still provides access to the flat top, giving the whole thing a curiously functional appearance, somewhere between an ancient monument and a surveying platform, which in a sense is exactly what it became.