This is a killeen, the Irish term for a children's burial ground, also known as a cillín. These were informal, unconsecrated plots used, from medieval times well into the nineteenth century, for infants who died before baptism, and sometimes for others considered ineligible for consecrated ground. The Catholic Church's doctrine held that unbaptised children could not enter heaven, and so they were quietly interred in liminal places: old ringforts, field margins, and small enclosures like this one near Kenmare Bay, on the edge of the parish rather than within it.

The site at Killeen is a compact one, measuring roughly 22.5 metres on its longer axis and just over 12 metres across. Field boundaries form its north-western and south-eastern edges, while rough lines of boulders mark the other two sides, giving the enclosure a sense of having been quietly but deliberately set apart from the surrounding pasture. Inside, upright grave-markers are arranged in regular north-east to south-west rows, a degree of order that hints at sustained, if unofficial, use over a considerable period. Towards the centre, a number of slabs lie flat among a scattering of stones. At the north-eastern end, two pillar-like slabs stand out: one reaching 85 centimetres in height, the other 65 centimetres. By the late nineteenth century the site had fallen out of use, its function quietly made redundant as attitudes to infant burial gradually shifted.