It looks, at a glance, like a collapsed field boundary or a natural prominence of the Burren's characteristic rock. It is neither. The cairn at Poulawack was in active use as a burial monument for nearly two thousand years, accumulating the dead from the Neolithic period through to the Middle Bronze Age, and the community that tended it kept returning, enlarging, and rearranging it across generations separated by centuries.

The earliest interment, radiocarbon-dated to around 3350 cal BC, is what archaeologists call a Linkardstown burial, a type of Neolithic megalithic grave named after a Co. Carlow site, typically containing a single crouched or disarticulated individual beneath a round mound. At Poulawack this burial sat at the centre, encircled by an inward-leaning revetment wall of uncoursed limestone slabs, the original cairn measuring roughly ten metres across. Then, around 2000 cal BC, cists began appearing within and around the mound. A cist is a small stone-lined box grave, usually housing a single burial with little or no covering monument of its own. Three were inserted at various points around the mound during this phase. The monument was enlarged again between roughly 1610 and 1432 cal BC: the cairn was raised by about a metre, extended by some four metres in diameter, and enclosed within a second outer revetment of closely set limestone slabs, each leaning slightly inward. Further cists were cut into the enlarged body of the mound. By the time the site fell out of use, ten burial deposits had been identified within it, containing the remains of around sixteen people, most of them unburnt. The excavation was carried out in 1934 by the Third Harvard Archaeological Expedition in Ireland, led by Hugh O'Neill Hencken, whose publication of 1935 remains the primary account of the site.

By 1997 none of the revetment kerbstones or burial features were visible above the surface, the cairn having been restored after excavation. A small modern standing stone, not present when the antiquarian T. J. Westropp visited in 1899, now leans on the summit. Two low drystone structures roughly ten metres to either side of the cairn are the surviving remnants of the excavation sheds Hencken's team put up in 1934. A second cairn sits approximately fifty metres to the north-east.