Built on the site of St. Patrick's 5th-century church, the Anglican cathedral dates from the 13th century, although much of the structure was built in the 1830s. Inside the church are the remains of an 11th-century Celtic cross, and a strange granite carved figure known as the Tandragee Idol, which dates from the Iron Age. A stone slab on the exterior wall of the north transept marks the spot where Brian Boru, the high king of Ireland who died in the last great battle with the Vikings in 1014, is buried.