Blaenavon is a town and community in Torfaen county borough, Wales, high on a hillside on the source of the Afon Lwyd. It is within the boundaries of the historic county of Monmouthshire and the preserved county of Gwent. The population is 6,055.

Until 1974, Monmouthshire, also formerly known as the County of Monmouth, was an administrative county in the south-east of Wales, on the border with England, and later classed as one of the thirteen historic counties of Wales. Its area now corresponds approximately to the present principal areas of Monmouthshire, Blaenau Gwent, Newport and Torfaen, and those parts of Caerphilly and Cardiff east of the Rhymney River.