It is a small detail that anchors a substantial building in a very specific moment: the era of the Penal Laws was loosening its grip, and Catholic congregations across Ireland were beginning, cautiously, to build in stone and with some architectural ambition. What survives at Templetown is a T-shaped structure whose layout, proportions, and surviving fabric speak to a community that was large, organised, and prepared to invest.

The church was raised to serve a notably extensive Catholic parish that, until 1863, encompassed not only Templetown but also Duncannon and Ramsgrange, a broad sweep of the Hook Peninsula in County Wexford. The T-plan, in which two transept arms cross the northern end of the nave, allowed a large congregation to gather around the altar at the crux of the building. There was a gallery above the southern entrance, reached by wooden stairs set against the inner face of the south wall, and holy water stoups were built into the east and west walls at ground level. The windows and doorways are round-headed and constructed in brick, a small touch of finish that distinguishes the building from purely utilitarian chapel architecture of the period. Granite crosses still surmount the east and west gables, though the south gable has not survived. The church remained in use for over a century before a new Catholic church at Templetown opened in 1898, at which point this one fell into disuse and began its slow decline into ruin.

The ruins sit on gently rolling ground with a road running close to the south. There is no evidence of a surrounding enclosure or of any burial ground attached, which makes Templetown unusual among Irish rural churches of its era, where a graveyard is almost taken for granted. The sacristy, added to the outside of the north wall, is still legible in the fabric, and the brick detailing of the window surrounds is worth examining closely where it remains intact.