"The church is built of the site of a monastery which was established about 560 by St Dunawd, the first abbot of the monastery. The monastery was destroyed in about 616 by Æthelfrith of Northumbria when 1,200 monks were killed and only 50 escaped. No trace of this monastery exists.
In about 1300 a sandstone church was built on the site of the monastery. The chancel from this building is still extant. The church was restored between 1723 and 1726 by Richard Trubshaw; this restoration included the bell tower. The north aisle was altered in 1832. The architect John Douglas was married in the church in 1860 and in 1868 he carried out a restoration of the church. In 1913 the vestry was built and the organ was repositioned. For further information SEE
http://en.wikipedia.org/wiki/St_Dunawd's_Church,_Bangor_Is-coed