The graveyard at Killomenaghan sits on the south-western face of a low hillock, and within it stand the poorly preserved wall footings of a medieval church. Around the graveyard, aerial photography has revealed curving earthworks that suggest the presence of an ecclesiastical enclosure, the roughly circular or oval boundary that typically defined a monastic settlement in early Christian Ireland. The difficulty is that the curves may simply follow the natural base of the hillock rather than any deliberate human construction, so the enclosure remains a possibility rather than a certainty.

The site is associated with St. Manchán, also rendered in sources as Managhan, Menaghan, and Moynaghan, a saint connected to the monastery at Lemanaghan in County Offaly. Local tradition held that a pilgrimage route once ran between Killomenaghan and the great monastery of Clonmacnoise, one of the most significant early medieval religious centres in Ireland, passing through the townland of Cloncraff, also known as Bloomhill. This was not merely a pious legend: excavations carried out in 1987 by Breen, Parkes, and Bradshaw uncovered partial remains of a trackway in that townland, lending the folklore a degree of physical credibility. Two holy wells dedicated to St. Managhan lie within the possible enclosure, and holy wells associated with a founding saint are a common feature of early monastic landscapes, often marking places of continued local veneration long after the formal religious community had disappeared. Elsewhere on the site, earthworks in the field to the north-west appear to be broad cultivation ridges of uncertain date, and what looks like a ditch to the south-west is probably a drainage feature rather than anything monastic in origin.