"[2] St Mary's Church is situated near the east coast of Anglesey, north Wales.

He added a vestry on the north side and a porch to the south, as well as making some other alterations and additions, such as the re-roofing of the chancel.

[8] The Welsh priest and poet Goronwy Owen, who was born in the parish on 1 January 1723, served for three weeks as curate of St Mary's.

[9][10] St Mary's is built from rubble masonry, with buttresses at the eastern ends of the nave and chancel, and it has a slate roof.

[2][11] Entrance is through the porch in the middle of the south wall of the nave, which houses a round-headed doorway from the 15th or 16th century.

The east window, which dates from the 15th century, has three lights headed with cinquefoils set within a pointed arch.

Cadw (the Welsh Assembly Government body responsible for the built heritage of Wales and the inclusion of Welsh buildings on the statutory lists) states that St Mary's has been listed because it is "a good rural church retaining substantial medieval fabric".

[2] Writing in 1847, the clergyman and antiquarian Harry Longueville Jones said that St Mary's, which he called "a rather long and low building", was situated "in an uneven, rocky, and exposed locality" within a parish that had a "peculiarly bleak and desolate appearance".

[13] He also thought that the roof of the church was "remarkable for the quantity of good, but light, timber used in its construction.