The ruined church at Moone went from being described as in good repair to ruinous within the space of fifteen years, which tells you something about how quickly the seventeenth century could undo centuries of careful maintenance. A royal visitation of 1615 found it sound; by 1630 it was gone to pieces. After that, the process of dismemberment continued well into the nineteenth century, when the Lady chapel and the north wall were pulled down in the 1830s. The belfry, recorded by Cooper in 1784 at the south-east corner of the building, collapsed sometime in the early 1800s. What remains is a long, narrow shell of uncoursed limestone rubble, roughly 28.8 metres by 5.7 metres, with a handful of dressed granite quoins at the corners. The east gable still stands to a height of seven or eight metres, as does the west, which retains two lintelled windows. At the west end of the south wall there is a lintelled entrance, and splayed windows survive in both the north and south walls, the kind of narrow single-light openings that let in a thin column of light without compromising the wall's structural integrity.

The church represents several centuries of building and rebuilding, with phases running from the tenth or eleventh century through to the fifteenth. It appears in the documentary record for the first time in 1179, when it was listed as belonging to the diocese of Glendalough, and sometime between 1220 and 1228 it was granted to St. Patrick's Cathedral in Dublin. That affiliation placed it within one of the more significant ecclesiastical networks in medieval Leinster, though the physical fabric of the building tells its own story of gradual accumulation rather than any single grand campaign of construction. The high crosses associated with the site, which are among the more celebrated early medieval stone carvings in County Kildare, are probably not standing in their original positions, a reminder that what looks like an ancient arrangement is often the product of much later intervention.