The first Parish Church of Callan was St. Brigid's church located in Kilbride just outside the town. This was replaced in 1206 by the Church of the Assumption. This church was probably built by the elder William Marshall, who was, also, most probably, the founder of Callan town. During the fifteenth century this church, with the exception of its square tower was taken down and replaced in 1460, on the same site by St. Mary's Parish church
This church originally consisted of nave and side-aisles, a chancel at the east end, and the square tower of its predecessor, which had been incorporated with it, at the west end. all the original walls, except that separating nave and chancel (which was added during a later period of remodelling) are still very well preserved; as are the eight graceful Gothic arches of the aisles, and the many traceried windows.
St. Mary's was restored in the 17th century by by three ladies of the Comerford family, known locally as the three shaughrauns and as they could not agree on one form of architecture for the church it has since boasted of three different styles.
Within its confines is buried Adam le Blund, the second husband of Dame Alice Kytler the notorious Kilkenny witch.