The Church of St Cynog stands in a large churchyard, in the centre of the village of Defynnog, just to the south of Sennybridge.

[3] The Clwyd-Powys Archaeological Trust survey undertaken in 1995 expressed doubt that the "Celtic" window in the church is actually a pre-Norman feature.

[2] Robert Scourfield and Richard Haslam, in their Powys volume in the Buildings of Wales series, date the tower to c.1500.

[6] The churchyard contains four ancient yew trees, one of which has been dated at roughly 3,000 years old, making them among the oldest in Britain.

[3] The church contains two carved stones of very early origin; in the porch is a Roman gravestone, incised with the wording, "Rugniatio Livendoni" and the font has an inscription, "Siwurd + Gwlmer" in Runic script in the Lombardic language.