St Derfel's Church is located on the northern edge of the village of Llandderfel, Gwynedd, Wales.

Derfel then became a monk and founded two churches, that at Llandderfel, and a chapel near Cwmbran in South Wales.

The village of Llandderfel stands in the eastern part of Gwynedd, equidistant between Llandrillo, Denbighshire and Lake Bala.

[1] The church has a combined nave and chancel with a porch and vestry forming a cruciform plan, with a bellcote.

[5] Richard Haslam, Julian Orbach and Adam Voelcker, in their 2009 edition Gywnedd, in the Buildings of Wales series, call the Ceffyl Derfel, "a medieval relic of exceptional rarity".