 The current building is medieval, with the western end possibly dating back to the 13th century.However, the presence of 6th century inscribed stones, and the dedication to St Tanwg, suggest much earlier use of the site as a church, possibly dating to around 453 AD as part of St Patrick's work to establish links between Ireland and Britain.St Tanwg's was extended to the east, including a tall east window and the addition of a rood screen, in the 15th century.