St Mary's church was built to replace the coastal medieval church of St Cwyfan (NPRN 27475) in 1870, to designs of architects Kennedy and O'Donoghue. It is located 1km inland on the east side of a minor road within a square churchyard. It is a rectangular building, continuous nave and chancel with gabled porch on the north-east lateral wall, and a bellcote above the south-west gable wall.
Sources: Haslam et al., Buildings of Wales: Gwynedd (2009), p.189.
http://www.celtic-circle.co.uk/llangwfn.html

David Leighton, RCAHMW, 14 November 2014