The markers are modest, small set limestone blocks arranged in north-south rows, and the burials beneath them run east to west in the traditional Christian orientation. The whole area forms an irregular L-shape, roughly eight and a half metres along its longer axis, with the greatest concentration of stones gathered towards the south-west corner. It is an understated place, easy to miss, and that quietness is part of what makes it worth understanding.

This is a cillín, the Irish term for an informal burial ground used for unbaptised infants and others considered ineligible for consecrated ground under Catholic Church practice. For centuries, such children were buried apart from the main parish graveyard, often in liminal locations: old earthworks, ruined churches, field boundaries, or, as here, the remains of earlier settlement features. The moated site at Castlebin belongs to a class of medieval enclosures common across Ireland, typically a roughly rectangular platform surrounded by a water-filled or dry ditch, associated with Anglo-Norman or later medieval settlement. That an early modern or post-medieval children's burial ground should occupy the southern half of such an enclosure is a familiar pattern; people instinctively chose places that already felt set apart. The limestone blocks serving as grave-markers are unworked and unpretentious, but their careful alignment in rows suggests that those who buried here were keeping their own kind of order, maintaining a record in stone even when the church offered none.