A machicolation is an opening through which defenders could drop stones or pour liquids on those below, and finding one positioned directly over a church entrance raises quiet questions about who the builders expected to keep out, and when.

The church at Ballycahill was already part of an established ecclesiastical landscape by 1302, when it appeared in the taxation records of the Diocese of Cashel, placing it firmly within the medieval administrative church of Munster. The building itself is of roughly coursed limestone with base-batter, a slightly splayed thickening at the base of the wall that adds structural stability, a technique common in Irish medieval construction. It was originally laid out as a nave and chancel church, but only the nave now survives intact. By around 1840, a length of the north chancel wall and a small fragment of the south chancel wall were still standing, though these have since been lost. The rectangular graveyard, large in proportion to the surviving structure, uses the church ruin as its northern boundary, a relationship between the living, the dead, and the partially demolished that feels characteristic of the Irish countryside.