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 upper-most part of the Afon Lwyd valley, at an elevation exceeding r000 ft., in a wild and mountainous district, on the eastern 32 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 .