The main structure is a roughly square platform, approximately twelve metres across, with a more clearly defined edge on its south-eastern side where stone facing still breaks through the turf. Projecting from its eastern corner is an elongated triangular bank, fifteen and a half metres long, its northern edge still lined with a single course of large boulders. Archaeologically, the whole thing is difficult to read; it clearly incorporates the remains of a church, but the full shape and purpose of the earthwork around it remains uncertain.

The townland name itself preserves the site's earliest identity. Killunagher derives from the Irish kill, meaning church or monastic cell, and the place has been identified by Gwynn and Hadcock, writing in 1970, as the early medieval foundation of Kill-Lunechair, associated with a saint named Lunecharia. That puts its origins somewhere in the period when small local churches and hermitages were being established across Ireland under the patronage of figures now largely forgotten outside their immediate localities. St Lunecharia is one such figure. Local tradition adds further layers: the earthwork is said to contain a souterrain, an underground stone-lined passage of the kind used in early medieval Ireland for storage or refuge, and the site was also used as a children's burial ground. Such grounds, known in Irish as cillíní, were places where unbaptised infants were buried outside consecrated ground, and they are found across the country, often reusing ancient or liminal sites. Roughly fifty metres away in the same field, a separate earthen bank runs for nineteen metres along the field's northern edge, with a cluster of hawthorn trees at its western end. Local tradition holds that a priest was hanged at that spot, a memory that, whatever its historical basis, suggests the field carried a weight of significance well beyond its present appearance.