At first glance, the graveyard on this gentle south-facing slope outside Kilmacthomas looks like a straightforward Church of Ireland burial ground, enclosed by its stone-faced earthen bank. Look more carefully at the ground to the south, however, and something older announces itself: a D-shaped, grass-covered area roughly 40 metres east to west and 27 metres north to south, its outline preserved as a slight scarp curving along the eastern, southern, and western edges. That subtle ridge in the turf is all that remains above ground of a much earlier ecclesiastical enclosure, the kind of roughly circular or oval boundary that typically surrounded early Irish church sites and their associated buildings.

This was once the parish church of Rossmire, also recorded as Kilcool, a dedication noted by the historian Power in 1897. The "kil" element in such place names generally signals an early Christian foundation, derived from the Latin "cella" by way of Old Irish, and referring to a church or monastic cell. By the time of the first Ordnance Survey in 1841, the church ruins themselves had already been cleared away entirely, a fact recorded by O'Flanagan in 1929. What the later rectangular graveyard now occupies, with its relatively modern Church of Ireland building, sits immediately north of where that older enclosure once stood. The two areas together, the surviving D-shaped earthwork and the present burial ground, suggest a site with a long and layered history of use.

About 140 metres to the south-east of the site, a natural spring known as St John's Well still exists. Holy wells dedicated to saints were frequently associated with early church foundations in Ireland, often pre-dating the formal ecclesiastical structures built nearby, and their continued presence on a landscape can be one of the more durable indicators of where a community's religious life was once centred.