St. Mary's Church located in Irishtown,Clonmel dates back to the 13th Century although extensively repaired in the 15th century.

The multisided tower is unusual. The grounds are bounded, on two sides, by the medieval town walls and towers.

Old St. Mary's Church is believed to have been built by William de Burgo in 1204c, the first reference to it is in a letter dated August 1228. In the 14th C the town was almost continuously under siege by the Irish. James Earl of Ormonde exclaimed in 1385 that "the citizens of the town had been unable to attend divine service in their parish church in a accustomed manner due to the poor state of repair of the building".
A fortified church was built on the site in the late 14th - early 15th C. Alterations were made in the 14th, 15th and 16th C. The main features which survive are the base of the bell tower 27 feet square and the East Tower House; square building with battlements and lancets. It was destroyed in 1650 during the Cromwellian occupation. The East window dates from the 1500s and is almost identical to a window in the Dominican Church in Cashel and the West window is a smaller version of the chancel window in Holycross Abbey. In 1805 major renovations took place and the octagonal bell tower was built to its present height of 84 feet on the base of the old tower. In 1857 a new roof was built at a height of 56 feet 6 inches and the foundation of the arches were strengthened.