A souterrain is an underground stone-lined passage, typically associated with early medieval settlements and ecclesiastical sites, used variously for storage, refuge, or both. The deliberate act of inserting a grave into such a feature speaks to the layered, long-accumulated nature of this ground, where the dead of successive centuries have been laid down on top of the structures of earlier inhabitants without apparent concern for the distinction.

The graveyard sits to the west and south-west of Rathborney church, and the majority of the enclosed area is taken up by a rath, or ecclesiastical enclosure, a roughly circular boundary that marks out the sacred precinct of an early Christian site. Within this compound, and spreading beyond it, graves are distributed across the full extent of the ground, including inside the church itself. The markers are a varied collection: cut headstones, flat slabs, occasional square-headed crosses, and pieces of masonry salvaged from the church fabric and pressed into secondary use as grave markers. The earliest inscription that can still be read dates to 1800, though the site is evidently much older. Eighteen metres south-south-west of the church, just outside the ecclesiastical enclosure boundary, sits a bullaun stone, a large stone with one or more rounded hollows ground into its surface, a type found across Ireland and typically associated with early monastic sites, where they may have served ritual, grinding, or healing functions.

The graveyard is bounded by a mixture of straight modern walls along the west and north sides and a curved modern wall running from east to south-west, giving the enclosure overall dimensions of roughly 75 metres east to west and 48 metres north to south. That curved wall is likely tracing, at some remove, the line of the older ecclesiastical enclosure beneath it, which is itself built into a landscape of considerably greater age.