What looks at first like a straightforward medieval church in a County Kildare graveyard reveals, on closer inspection, a quietly peculiar piece of ecclesiastical engineering. Attached to the west gable is a later tower, barely 1.7 metres wide from east to west, three storeys tall, and built around a staircase contained entirely within the wall itself. This intramural stair, running up inside the masonry rather than through a separate interior space, served a specific purpose: doorways at the upper levels opened onto wall-walks running along the north and south sidewalls of the church, giving access to the full length of the building at height. It is an arrangement more often associated with defensive structures than with a parish church dedicated to the Virgin Mary.

The church sits within a graveyard and measures roughly 15.8 metres along its east-west axis and 7.1 metres across, constructed from uncoursed rubble limestone with walls around 1.2 metres thick. The layout is symmetrical in several respects: doorways face each other across the nave from the north and south sidewalls, and window openings are paired at the east ends of those same walls, with a further window in the east gable. A double bellcote, a small wall-mounted structure designed to hold one or more bells, sits atop the west gable and is incorporated into the base of the later tower. The building was restored between 1979 and 1980. Historically, this church was dependent on the church at Old Kilcullen, a site known in early sources as Omurethi, which served as the superior or mother church in the ecclesiastical arrangement of the area. Inside the restored structure, an effigial tomb survives, a carved monument bearing a sculpted figure of the deceased, a type of memorial that in an Irish medieval context often marks a person of local significance, though the identity here is not recorded in surviving sources.