What makes Brickendown quietly stranger is the accumulating evidence of things no longer there: a narrow cut-limestone window that early observers carefully measured and recorded, a stone-cut baptismal font last noted in a nearby farmyard, and buttresses at the east gable that only survive in the written record of a local writer from 1892. The church itself is a simple, undivided rectangular structure, roughly 14 metres north to south and just under 6 metres east to west, built from coursed limestone rubble and aligned east to west in the conventional manner of early Irish ecclesiastical buildings.

The best-surviving section is the south wall, which reaches nearly 2.7 metres above exterior ground level near the east gable and extends around 9.8 metres from the south-east angle, though it is now heavily overgrown with ivy and scrub. An entrance, roughly 1.5 metres wide, sits at the west end of that same wall. The east gable retains two buttresses, projecting supports built against the wall to resist outward pressure, with the southern buttress standing nearly 3 metres high despite its own covering of ivy, and the northern one somewhat lower and in poorer condition. A reference in the Ordnance Survey Letters, compiled by O'Flanagan in 1930, records a small window in the south wall, placed about 1.27 metres from ground level and measuring a notably narrow 17 centimetres in width. No physical trace of it now remains. Similarly, a stone-cut font mentioned by Cahill in 1982 as being visible in a neighbouring farmyard has since disappeared from view. What was observed and measured at one point in time has a way of vanishing here, leaving the site as a record of its own gradual erasure. The church sits within a cluster of enclosures, with three immediately to the south and south-east and a further one some 200 metres to the west, suggesting this was once a more substantial ecclesiastical or agricultural complex than the low grass-covered walls now suggest.