RHYMNEY an urban sanitary district of Monmouthshire, on the borders of Glamorganshire, is situated in the valley of the Rumney river, 20 miles west of Abergavenny, and 22 north of Cardiff. It owes its importance to the neighbouring coal mines and to its iron and steel works, which employ nearly the whole population. The works of the Rhymney Iron Company, including blast furnaces and rolling mills, are among the largest of the kind in England. The town consists chiefly of plain houses inhabited by workpeople, the principal building being the church, a handsome structure in the Doric style erected in 1842. The population of the urban sanitary district (area 2890 acres) in 1871 was 8138, and in 1881 it was 8663.