St John's church is located towards the north-west end of Llangollen on the south side of Abbey Road (the A539), set back from the road in a churchyard used as a cemetery. It was built in 1858 as a cemetery chapel, a facility for the burial ground called Mynwent y Ddol (?The Meadow Cemetery?), which was then new. The town's main services were held at the parish church of St Collen. Later in the nineteenth century, St John's Church became the place of worship for people who wanted services in Welsh, English having become the main language at St Collen's Church. It continues to provide Welsh-medium services today. The church's architecture lacks the ornamentation commonly seen on Victorian churches, perhaps a conscious effort to counter the drift of Welsh people towards Nonconformism and its plain chapels.
The church is constructed of coursed sandstone under a slate roof. It consists of a single chamber, chimney stack at the north-west corner, gabled north-west porch with diagonal buttresses, and a small west bellcote, and is lit through cusped lancet windows.
Sources:
http://historypoints.org/index.php?page=st-johns-church-llangollen
E.Hubbard, Buildings of Wales: Clwyd (1986), p.220.
Google Street View, July 2015.

David Leighton, RCAHMW, 2 October 2015