St Mary's Cathedral () is a cathedral church of the Diocese of Tuam, Limerick and Killaloe in the Church of Ireland. It is located in Tuam, County Galway, in Ireland. From the 12th century until 1839, both before and after the Reformation, it was the seat of the former Archdiocese of Tuam. Most of the present structure dates from the 1870s, but parts of earlier 12th- and 14th-century structures survive within. Origins The founder and first bishop of Tuam is considered to be St Jarlath, who founded the church about 501. The traditional date of his death is 540. However, the names of only two other bishops of Tuam are recorded before the 11th century, Ferdomnach (died 781) and Eugene mac Clerig (died 969). The medieval importance of Tuam was chiefly the result of its becoming the seat of the O'Connor High Kings of Ireland in the early 11th century. The O'Connors had previously been based at Cruachain, County Roscommon. The first cathedral on the present site was begun in the 12th century, when Turlough O'Connor (1088–1156) was High King. This marked the establishment of Tuam as the seat of an archbishop, an event which followed the Synod of Kells of 1152. The first cathedral lasted only a few years and was destroyed by fire in 1184, recorded thus in the Annals of Lough Cé: "The great church of Tuam-da-Ghualann fell in one day, both roof and stone". After this, no rebuilding was attempted for some one hundred years, except that in the 13th century a small parish church was built on the site of an old monastery. This long delay was largely the result of the Norman invasion of Ireland, which left the city of Tuam in ruins. In the 14th century, a second St Mary's Cathedral was begun, a little to the east of the original building and incorporating into its entrance the remains of the 12th-century chancel and sanctuary. Present cathedral With the coming of the railway to Tuam in 1861, and the enlargement of the garrison, the town's Anglican population increased and this led to the building of a third cathedral on the site, designed by the architect Sir Thomas Newenham Deane, which was begun in about 1861 and completed in 1878. Charles James Seymour was the Dean at the time. The new or third cathedral was built on the site of the first cathedral and