Built into the west gable, it is a flat-headed trabeate doorway, meaning one spanned by a horizontal lintel rather than an arch, a form associated with early medieval construction in Ireland. The doorway dates the earliest phase of the building to perhaps the 10th or early 11th century. Its exterior face, however, has been entirely obscured by an 18th-century mausoleum built flush against the gable wall, complete with crenellated parapets and a vaulted interior. The result is an architectural palimpsest: one building swallowing the evidence of another.

The site's history reaches back considerably further than the stonework. The 7th-century Tripartite Life of St Patrick records that a bishop named Olcan, a disciple of Patrick, came to reside at the place then known as Cell-mor-Uachtar-Muaide. The current structure belongs to a much later era, though the tradition of sanctity on the site clearly persisted. By 1306, the church appeared in the Ecclesiastical Taxation as a parish church, valued at 3 marks. The building was extended eastward during the later medieval period, a shift legible in the masonry itself: the eastern section of the north wall is built from smaller limestone rubble, noticeably different from the large squared blocks used in the earlier construction. A second doorway was added in the south wall, probably during this same later phase. When Ordnance Survey workers described it in 1838, its pointed arch was still intact, though they noted the surrounding masonry was of markedly inferior quality compared to the older fabric. That upper portion has since collapsed, though the drawbar socket, the slot cut into the jamb to receive a locking bar, remains visible in the west jamb.

The wider site rewards attention beyond the church walls. Roughly 150 metres to the west lie a circular enclosure, a bullaun stone, and a cross-inscribed stone. A bullaun is a boulder or outcrop with one or more artificial cup-shaped hollows, often associated with early ecclesiastical sites and sometimes with folk ritual use. A holy well sits approximately 180 metres to the south-east. The church interior now holds two 19th-century table tombs among the rubble, and box tombs are ranged along the exterior of the north wall. The ivy that currently engulfs much of the standing fabric, which reaches between 1.6 and 1.8 metres in height, makes close reading of the masonry difficult, but the broad sequence of construction is still traceable for anyone willing to look carefully at the corners and the changing character of the stone.