Little is known of the early history of the Desmond Tower. Built circa 1400, it appears to have been incorporated into the outer perimeter of the Friary grounds. Some say it was built by the Earl of Desmond to offer protection to the Franciscan Friary, while others suggest he retired there following the death of his wife.
In recent history, it was incorporated into St Mary’s church by the architect Charles Cottrell. However, integrating the Desmond tower, a genuine element of medieval architecture, into his new church, posed particular challenges for Cottrell.
On the east side of the new church, Cottrell does not use finely cut ashlar blocks but a more coarse rubble so that the east gable, transept and east wall of the nave would better resemble the building techniques used in the medieval Desmond tower. This contrasts with the south and west elevations where he uses finely cut blocks laid in regular horizontal courses.