St Dwywe's Church at Llanddwywe, within the community of Dyffryn Ardudwy, was built on an ancient mound which is at the end of the straight line followed by the road to Cors-y-gedol Hall. This line runs straight and true to a cairn on the side of Moelfre, and it is suggested that this is a prehistoric man-made creation relating to the summer solstice rather than a more recent addition. The church is a Grade II listed building.