It measures about twenty metres north to south and seventeen metres east to west, rising barely a third of a metre above the surface. That modest elevation is easy to dismiss as a trick of the landscape, but what lies beneath, and what the site was used for within living memory of the 1830s, gives it a quiet weight that its physical presence alone does not suggest.

The site is reputed to occupy the ground of the monastery of Killansnamh, said to have stood directly opposite Narrowwater Castle on the far bank of the Newry River. Around 1837, some visible remains of the abbey were apparently still standing, or at least recognisable as such. By that time the place had long taken on a secondary function common to early monastic sites across Ireland: it served as a cillín, an informal burial ground for unbaptised infants. Under Catholic theological convention of the period, children who died before baptism were considered unable to enter consecrated ground, and so communities quietly interred them in liminal places, old ruins, boundary ditches, or sites already touched by an older sanctity. At Cornamucklagh, the crumbling fabric of a medieval monastery provided exactly that kind of ground, set apart from the parish churchyard yet freighted with its own spiritual associations.