Brynmawr, a market town of Brecknockshire, Wales, 14½ m. S.E. of Brecknock and 156 m. from London by rail. Pop. of urban district (1901) 6833. It is on the London & North-Western and Rhymney joint railway connecting Rhymney and Abergavenny, being also a junction for a branch line to Pontypool via Blaenavon, and the terminus of the Great Western line from Newport via Nantyglo. The town owes its origin to the development during the first half of the 19th century of ironworks at the upper ends of the valleys that converge in its neighbourhood, its site being previously known as Waun Helygen (Willow-tree Common). The Nantyglo ironworks afford occupation to large numbers of the inhabitants of Brynmawr. Both coal and iron ore were formerly worked, but the coal is exhausted and the ore unsuitable for modern processes. Brynmawr was formed into an ecclesiastical parish in 1875 out of portions of the civil parishes of Llanelly and Llangattock. In 1894 this was formed into an urban district, which was enlarged in 1900 by the addition of a portion of the parish of Aberystruth in Monmouthshire, the whole being at the same time consolidated into a civil parish.