St John’s Cathedral of Sligo Town dates from the mid-18th century, though it is located on the site of a 13th-century hospital and parish. The cathedral’s west tower is thought to contain remnants of the original structures.

Renowned architect Richard Cassels designed the present cathedral, taking inspiration from early-Roman style basilicas. The structure, however, was significantly altered in the 19th century, as the original Romanesque windows were replaced and the chancel was extended.

St John’s, which was elevated from church to cathedral in 1961, also has a connection to the famous Yeats family. The parents of W.B. Yeats married there in 1863, while the grave of his maternal grandparents is located near the west door of the church. There are memorials to various family members within the house of worship as well.