BLAENAVON, or Blaenafon, an urban district in the northern parliamentary division of Monmouthshire, England, 15 m. N. by W. of Newport, on the Great Western, London & North Western and Rhymney railways. Pop. (1901) 10,869. It lies in the uppermost part of the Afon Lwyd valley, at an elevation exceeding 1000 ft., in a wild and mountainous district, on the eastern edge of the great coal and iron mining region of Glamorganshire and Monmouthshire. There are very extensive iron and steel works, with blast furnaces and rolling mills in the district, which employ the large industrial population.