Machen is a large village and ancient parish in Monmouthshire, three miles to the east of Caerphilly. It neighbours Bedwas and Trethomas. It lies on the River Rhymney which forms the county border with Glamorgan. The ancient parish lies across the river in both counties and has a total has a population of 4,698, 639 of which are in the township of Rhyd-y-Gwern in Glamorgan.
Machen Mountain provides a spectacular backdrop to the village. It is possible to walk up to and along the top of the mountain, where a number of large boulders were present. These were explained in local folklore as follows:
Saint Peter was visiting in order to watch over the Faithful. Taking offence at the sudden appearance of the Devil, he picked up a large number of boulders and placed them in his apron so as to carry them more easily. He then gave chase to the Devil, both chaser and chased (having the stature of giants) leaping from mountain-top to mountain-top. As the Devil alighted on Machen Mountain he paused to catch his breath, whereupon Saint Peter began hurling the rocks at him, leaving a considerable amount of debris around his adversary in the process. The area of rocks is known to this day as "The Devil's Apron Strings"
Machen was a village rooted in the iron and coal industries stretching from the 17th century. Machen Forge was an early adopter of the Osmond process for the production of wrought iron.
Machen was a station on the Brecon and Merthyr Railway and a branch to Caerphilly on the Pontypridd, Caerphilly and Newport Railway, closed to passengers in 1956.
Famous people from Machen include the politician Ron Davies and Alfred Edward Morgans, Premier of Western Australia for just 32 days in 1901.