St Mary's church was situated on the south side of Stryd-y-Mynach, some 180m north-east of the junction of the A497 and the B4417 in the centre of Nefyn. Formerly the parish church it is now re-used as a maritime museum. It was a nineteenth-century, Late Georgian, church built c.1825-7, on the site of a former church whose registers date from 1694, but with a more ancient history as a church established here in the fifth century by Nefyn ar Nefain, daughter of Brychan Brycheiniog of Garth Madryn. The name was recorded as Llanfair-yn-Nefyn in the twelfth when the church was held by Augustinian Canons of Haughmond Abbey. In the thirteenth century a priory was attached to the church.
It is constructed of rubble stone with a grouted slate roof and consists of nave and chancel in one, thin west tower and a gabled, buttressed north porch added later. The tower is square, plain and sheer to a set-back under the bell-stage, then simple stepped cornice under parapet which has angles ramped up to small corner finials surrounding a sailing-ship vane. The bell-stage has a single large louvred opening each face, slightly pointed with stone voussoirs. The main part of the tower has a blocked circular opening at the top of its west face, probably for a clock. A broad pointed original west door is now blocked with an inserted window. The body of the church has two pointed windows to each side, with plain timber Y-tracery and a large similar east window of three lights. Inside, the six-bay roof has arch-braced collar trusses and triple purlins. All fittings have been removed.
Sources:
Cadw Listing description.
R.Haslam, J.Orbach & Adam Voelcker, Buildings of Wales: Gwynedd (2009), p.478-9.

RCAHMW, 16 March 2016

Commenting as part of the crowd-sourcing project Crwydro in 2014, a user posting a picture under the name *waen noted that the church currently houses the Ll?n Maritime Museum.

(Source: Crwydro, 17.07.2014)