The beautiful Clydach Gorge (also known as Ceunant Clydach) is a steep-sided valley down which the River Clydach flows to the River Usk. It runs for 5.6 kilometres (3.5 mi) from Brynmawr in Blaenau Gwent to Gilwern in Monmouthshire. The gorge is a site of special scientific interest due to its unique industrial landscape and rock strata.
By the 17th Century it was becoming industrialised, the Llanelly furnace and forge had been established at Maes Gwartha and, by 1684, were producing quantities of iron and charcoal. By 1693 Clydach House had been built along with a number of workers’ cottages. The Clydach Iron Works, founded before 1795, followed the recent introduction of coke as fuel and up until the 1860’s employed over 1350 people many being children under the age of 13. The valley has the densest network of surviving early tram road routes anywhere in Britain.