Round towers, the tall free-standing structures associated with early Irish monasteries and used variously as bell towers and places of refuge, are common enough across Ireland, but finding one cannibalised into the fabric of a later building is considerably rarer. Only the lower three metres are thought to be original early medieval fabric; the rest was reconstructed during the thirteenth century when the nave went up around and against it.

The church is dedicated to Saints Peter and Paul, a dedication recorded from the thirteenth century, and it appears to have replaced an earlier pre-Norman foundation, of which that tower base is the principal surviving evidence. What stands today is a substantial structure: a thirteenth-century nave and chancel with wide aisles that may have been added in the fifteenth century, along with a thirteenth-century south transept. The building is constructed of roughly coursed limestone, though the east wall and the area below the chancel windows show more carefully worked dressed masonry. The glazing arrangements are worth studying closely. The east gable contains a five-light window of slender graduated lancets, and the chancel is lit from the south by three twin-light cusped pointed windows. A large triple-light window with switch-line tracery, a late Gothic technique in which window tracery curves and crosses in flowing patterns, sits near the west end of the south aisle. A fifteenth-century south porch has since disappeared, though the pointed south doorway with its ogee-headed hood mould, a decorative frame with a double-curved profile, survives.

The church is a designated national monument, listed as No. 408, and sits within Kilmallock town in County Limerick, a place that retains a striking concentration of medieval fabric including town walls and a Dominican friary. The ruins are accessible and worth a methodical circuit: the north aisle, lit by three twin-light and one single-light narrow windows, has a quieter, more austere feel than the more elaborately fenestrated south side. The transept has two widely spaced lancets in its south wall, with blocked openings in the east and west walls hinting at alterations over time. The round tower base is most clearly seen from outside the west wall, where it projects beyond the building line and gives a tangible sense of the layered occupation of this site across several centuries.