The third edition of the Ordnance Survey six-inch map, surveyed in 1933, recorded a modest rectangular enclosure measuring eighteen metres east to west and ten metres north to south. It was marked as a children's burial ground. Today, no visible surface trace survives.

Places like this are known in Ireland as cillíní, informal burial grounds used for centuries to inter unbaptised infants and others who, under Catholic canon law, were excluded from consecrated ground. The Church taught that without baptism, a soul could not enter heaven, and so these children were quietly buried apart, in marginal spaces: beside old boundaries, near water, at the edges of fields, or in the vicinity of ancient earthworks. The Ballydonnellan site sits roughly two hundred metres northeast of a ringfort, one of those circular enclosures of raised earthen banks that dot the Irish countryside and date broadly to the early medieval period. The proximity is not unusual. Cillíní were often placed near older, pre-Christian monuments, perhaps because such sites already carried a sense of otherness, of existing outside the ordinary run of the world.

The 1933 map marks the outline with enough precision to suggest it was still legible at that point, or at least that some local memory of it persisted. Whatever boundary or depression once defined the rectangle has since been absorbed into the pasture. That disappearance is itself part of a wider pattern: as the theological pressure around infant burial gradually lifted through the twentieth century, and particularly after the Catholic Church quietly revised its position in later decades, the careful tending of cillíní became less pressing, and many such sites faded back into the landscape that had always half-concealed them.