The grade II* listed church, a place of pilgrimage, is dedicated to Saint Cynog, a son of Brychan Brycheiniog, and was founded in the 5th century.

It is situated on the land between the valleys of the Ysgir Fawr and the Ysgir Fach which penetrate northwestwards into the uplands of Mynydd Epynt from the River Usk some miles to the south.

The community includes the hamlet of Upper Chapel which lies a couple of miles to the northeast.

To the north and west of Merthyr Cynog is the Army's extensive Sennybridge Training Area or 'SENTA'.

[4] For elections to Powys County Council, Merthyr Cynog is part of the Yscir electoral ward.