The building was constructed to span the full width of the ridge, and the southern edge of that ridge drops away sharply. At some point, probably gradually, that steep fall did what gravity tends to do: the wall built right on the lip of it collapsed. The north wall and both gables have fared considerably better, and the roofless shell that remains gives a remarkably clear picture of a 13th-century parish church, complete with a projecting west belfry whose upper storeys are gone but whose bonding stones still jut from the gable face, marking where the tower once locked onto the church wall. Eighty metres to the west, a tower house occupies the same low landscape, making this a corner of south Mayo that was once rather more organised and inhabited than the quiet pasture around it now suggests.

The site carries a name, Ceann Lacha, that appears in the Annals of the Four Masters in connection with the death of St Siadhal Ua Commain, recorded as Abbot there. The annals give the year as 794 AD, though scholars Gwynne and Hadcock, writing in 1970, corrected this to 799. There was some confusion over the centuries about where exactly Ceann Lacha was located, with Kinlough in Co. Leitrim considered first before the identification settled on this Kinlough in Co. Mayo. The present structure dates to the 13th century and is a National Monument in state ownership. Conservation work carried out by the Office of Public Works has included repointing of the surviving walls.

The details that reward a closer look are quiet ones. In the surviving stub of the south wall, at the southeast angle, there is a small aumbry, a shallow wall-cupboard used to store sacred vessels, built with considerable care: each of its four sides, top, and base formed from a single stone with chamfered edges. The east gable retains a trio of slim lancet windows, narrow pointed windows typical of 13th-century ecclesiastical building, though the arrangement is now incomplete; only the southernmost lancet is fully intact, and the central one has lost its pointed arch. Inside, a doorway at first-floor level in the west gable once connected the clerics' upper-storey accommodation directly into the belfry tower, a small architectural detail that says something about how carefully the building's interior life was organised, even here on a windswept knoll above a Mayo river.