St Mary's Cathedral, Tuam, Anglican cathedral in Tuam, Ireland.

St Mary's Cathedral in Tuam is an Anglican cathedral in County Galway, built in the Gothic Revival style with a medieval chancel and a Victorian nave. The chancel section is made of red sandstone and features a rounded Romanesque arch, while the nave was rebuilt in the 19th century in a contrasting style.

St Jarlath founded a church at Tuam around 501. The first cathedral on this site was begun in the 12th century under High King Turlough O'Connor, after the Synod of Kells of 1152 made Tuam an archbishopric; it burned in 1184. A 14th-century cathedral followed, and the present building, designed by Sir Thomas Newenham Deane, was begun about 1861 and consecrated on 9 October 1878.

The red sandstone chancel arch inside the building dates from the 12th century and is one of the rarest surviving examples of Romanesque work in Ireland. Visitors notice the sharp contrast between this old section and the Victorian-era nave that surrounds it.

The cathedral opens to visitors on Friday mornings and afternoons during summer, so it is worth checking ahead if you are planning a visit outside that period. The interior is compact and easy to navigate on foot, with the Romanesque chancel visible directly from the entrance.

The 12th-century Hiberno-Romanesque chancel arch is the only surviving part of Turlough O'Connor's cathedral, which burned in 1184. In the 14th century the De Burgo family built their new cathedral east of it, and the arch served as that building's entrance, blocked by a stone-and-wood structure with a door for over 500 years. It became the chancel again only in the 19th century.