The Church of St Mary Caerhun is situated in a beautiful location on the west bank of the River Conwy in the village of Caerhun, North Wales. The church which dates from the 13th century was probably founded by the Cistercians of Maenan Abbey.

The church is renowned for being on the site of the Roman fort Canovium and indeed it is thought that the sandstone used in the walls of the church probably came from Cheshire having been part of the Roman fort. It is thought that the present knave formed the original building. A porch and chancel were added in the 15th Century. It is believed that the east window was moved from the end of the original building to its present position above the altar. In the 19th century the porch was converted to a vestry thus the original south entrance is now the vestry door. In the 16th Century the wall containing the present entrance was rebuilt.

The entrance door is 18th Century studded plank and the lych gate is of the same period. Above the door there is a weathered medieval stone panel of a crucifix. The bell cote is of an unusual double style, although there is no evidence of there ever being more than one bell. The south transept or chapel was added in the 16th Century. A weathered stone on the outside of the chapel is dated 1591 and inscribed with the initials EW and GW as well as the Gwydir Arms. Inside the church, a board, inscribed in Latin, indicates that the chapel was built in 1591 by Edward Williams of Maes Castell who was High Sheriff of Caernarfon in 1570.

In both the 19th and 20th Centuries renovations were carried out. In 1972 a medieval Holy Water stoup and some bones were discovered in the north wall near the entrance. One theory is that they were hidden by supporters of the Old Faith during the Reformation. The stoup is now sited to the right of the door inside the church.