Towering over the town of Barmouth is the cathedral sized church of St John the Evangelist, primarily funded and furnished by the Perrins family of Lea & Perrins Worcester sauce, it is well worth the climb up the hill to visit.
The parish church is dedicated to St Celynnin.
The church dates from the 13th century and was extensively restored and probably extended in the late 15th or early 16th century. It had minor restorations in the 19th and 20th centuries but retains most of its medieval character. There is a 17th century porch and bellcote at the south end, with a bell inscribed with the date 1660.
The interior of the church includes 17th century wall paintings with texts and a skeletal figure. The benches date from about 1823 and record the names, addresses and occupations of their 19th century occupants.
The church is disused.
Llangelynnin sits on a slope above Cardigan Bay to the north of Tywyn. The A493 road and Cambrian Coast railway pass through the village, although the railway station closed in 1991.
The poet and scholar John Morgan was born in the village and Abram Wood, a famous Welsh gypsy, was buried there in 1799.