The site is recorded on the 1921 Ordnance Survey six-inch map under the name Killeen, a word that in Irish contexts typically denotes an unconsecrated burial ground for unbaptised children. That quiet designation tells much of the story: what was once, in all likelihood, an early monastic cashel, a roughly circular stone enclosure of the kind used to define and protect early Christian settlements, became in later centuries a place where families brought infants who could not be buried in consecrated ground.

The cashel measures roughly 32.6 metres east-west and 31.7 metres north-south. A ruined church occupies its south-east quadrant, and immediately south of that church there is a cross-slab and what appears to be a slab-lined burial. By the time the Ordnance Survey Letters were compiled in 1838, the site was already being described as a children's burial ground. The nineteenth century left further marks: field walls from a nearby settlement of vernacular stone houses, the ruins of which survive about 30 metres to the north, cut across the north-east of the cashel interior, and the north wall of the ruined church was incorporated into one of them. The south-facing slope below the cashel, sheltered and relatively fertile by the island's standards, still shows the ridged traces of cultivation from that same period. A holy well lies roughly 20 metres to the south-west, and on the slope below the cashel there are four possible clochans, small dry-stone beehive huts associated with early monastic life, arranged on a rough north-south line alongside at least one other unidentified structure.

Duvillaun More is an uninhabited island, and reaching the site requires landing by boat. The cashel's setting on the central ridge means it is approached across open ground, with bedrock breaking through the surface in places within the enclosure itself. The layering of the place is visible at ground level: early Christian stonework beneath nineteenth-century field walls, a monastic enclosure repurposed for the burial of the unbaptised, the whole of it slowly returning to grass and rock.