Known in Irish as Cill Bhreac, or Kilbrack, this roughly rectangular raised ground served for centuries as a cillin, the informal burial place reserved for unbaptised infants. Catholic doctrine long held that unbaptised children could not be interred in consecrated ground, and so communities across Ireland maintained these separate, liminal spaces, often ancient enclosures or marginal land, where the smallest of the dead were laid without ceremony. At Kilbrack, local tradition records that such burials continued into the early twentieth century, and the numerous low upright grave-markers that still break through the overgrowth confirm a long, sorrowful use.

The site measures roughly 20 metres north to south and 36.5 metres east to west, sitting about three-quarters of a metre above the surrounding ground level for much of its perimeter, though its northern edge is almost level with the field outside. Boulders define the eastern boundary. In the south-western quadrant, the remains of a rectangular structure survive, its walls reduced largely to a low band of collapsed stone, though some original facing can still be made out on the eastern side; an entrance gap of about 0.7 metres is visible near the western end of the southern wall. The structure's internal dimensions of 8.7 by 4.2 metres suggest a small building of some kind, possibly an early ecclesiastical cell, which would be consistent with the Cill element of the place name, cill being the Irish word for a church or monastic cell. What lifts the site into genuinely unusual territory, however, is a large boulder sheltered beneath a tree in the northern half of the interior. On its sloping upper surface, divided by a natural fissure, are prehistoric rock art motifs: fourteen cupmarks and four cup-and-ring marks. Cupmarks are simple hollows pecked into stone; cup-and-ring marks surround those hollows with one or more concentric carved rings, and both forms are characteristic of prehistoric rock art found widely across Atlantic Europe. Their presence here suggests the ground held significance long before any Christian burial took place upon it.