The church in Llanfaethlu was built in the 15th century, probably on the site of an older building, because the temple in Llanfaethlu was already recorded in 1254 (Norwich taxation). It was dedicated to Saint Maethlu, an early Christian saint known as Maethlu the Confessor who, according to tradition, founded a hermitage or a small monastery south of the present church. In the 18th century, the first known early modern modifications of the church (northern nave windows) took place, possibly in 1760, when a new bell was founded. In the nineteenth century, the rectangular chancel of the church was thoroughly rebuilt, and the entire building was renovated at the beginning of the twentieth century.
The Late Gothic church consisted of a rectangular nave, and perhaps a separate chancel. The nave had three bays covered with an open roof truss and was built in the English Perpendicular Gothic style. In its southern wall, two two-light windows were pierced, consisting of openings topped with cinquefoils, set in rectangular frames. Also in the southern wall there was an entrance portal, preceded by a porch, probably from the period of the construction of the church. Inside, on its sides there were stone benches.
Today the church belongs to a group of well-preserved, small, rural late Gothic churches. This applies especially to the walls of the nave and porch, while the chancel was built in the nineteenth century, perhaps on the site of an older one. An original, reset window from the 15th century was embedded in its walls. In addition, Gothic windows have been preserved in the southern wall of the nave.
Salter M., The old parish churches of North Wales, Malvern 1993.
Website britishlistedbuildings.co.uk, Church of St Maethlu. A Grade II Listed Building in Llanfaethlu, Isle of Anglesey.