What looks like a single late nineteenth-century building is, on closer inspection, a layered structure in which an earlier place of worship was quietly absorbed rather than cleared away. At roughly 1.25 metres above ground level, the masonry changes character: large, roughly faced boulders give way to later stonework, marking the moment when an older church was not demolished but built upon. Even the blocked sillstone of an original lancet window, a tall, narrow window typical of medieval ecclesiastical architecture, is still visible in the east gable, its replacement inserted on a slightly different alignment as though the builders could not quite commit to erasing what came before.

The site is reputedly that of a monastery founded by St Leo in the seventh century, and the layers of the building seem to carry that long occupation forward in physical form. When the geologist George Kinahan visited in 1869, he found the east wall of the older church still standing, complete with its lancet window and portions of the north and south walls. The later church, built sometime in the nineteenth century, incorporated those surviving walls rather than starting fresh, though the reuse of the earlier south wall as a foundation plinth meant the new building ended up narrower than its predecessor. The result is an oddly asymmetrical structure: two unevenly spaced lancet-like windows punctuate the south wall, only one window sits slightly off-centre in the north wall, and a doorway that once opened between the southern windows was subsequently blocked up and plastered over, leaving the west gable as the sole entrance. Research excavations carried out in 2010 by Kuijt and colleagues added another discovery to the site, uncovering an associated graveyard that had not been previously documented. Two carved stones once associated with the chapel, known as St Leo's Cross or Leac Leo, and a broken cross-slab recorded by Crawford in 1913, have since disappeared from the site entirely.