St Mary’s church by the white hazel pool, near the fierce whirlpool with the church of Saint Tysilio by the red cave.
Tysilio was the son of Brochfael Ysgythrog, king of Powys. He fled his father's court to follow the religious life, eventually coming to Anglesey where he founded a hermitage on an island in the Menai Strait around 630AD.
After seven years he moved on to become Abbot at Meifod, Powys, where he had started his religious training. He is thought by many to be the same person as St Suliac, who set up a religious centre in Brittany.
As with all early religious sites, the original buildings are long gone. The current building dates to the early 15th century, but extensive restorations were done in the 1890s. The window at the east end of the church was installed at this time, but is a reproduction of the original 15th century one. The original wooden trusses for the roof were preserved. The octagonal baptismal font originates from the 14th century.
One unusual but attractive feature is the main door. The opening in the wall is rectangular, with a fitting door, but a massive oak frame with a round arched top has been fitted around the door.
As with most churchyards, there is a great deal of historic interest amongst the graves on the island. The cross section of graves come mostly from local families, but there are graves of some of the workmen who worked on construction of the bridges who either died during construction or settled in the town after work was completed. Welsh bard Cynnan is buried on the island as are members of the Davies family, who were successful local entrepreneurs during the 19th century.
On top of the highest point of the small island is a memorial to the local men who died during the World wars. This is also the best place on the island from which to view the Menai Strait and the two bridges that cross it.