obtaining iron ore, limestone and coal further up the valley. These ironworks had a great influence on the industrial and social developments of the surrounding area. Due to this, building began on buildings for settling the workers at the end of the 18th century, increasing house production during the 2nd quarter of the 19th century. The works could be approached over a cast iron bridge, Smart's Bridge (built in 1824). Production continued up until around 1860, where it was the main point of activity within the gorge. The works were associated with the Frere family (which included Sir Bartle Frere, born in Clydach House in 1815). The remains of two large masonry furnaces from the 1790s and the base of a later furnace can still be seen together with other structures thanks to an excavation carried out in 1986. Limeworks Blackrock Limeworks These limeworks were the first established in the gorge, having started production in 1794/95. From Blackrock, the quarry extends along the contours of the gorge above Clydach North (also referred to as Cheltenham). They continued to work until 1908 and the masonry limekilns remain today. Clydach Limeworks The limeworks at Clydach (OS grid ref SO 233127) were built in 1877 to provide lime for the construction of the nearby Nant Dyar railway viaduct. Two pairs of limekilns remain against an impressive quarried backdrop. Llanelly Limeworks Llanelly Quarry supplied the Clydach Ironworks with limestone, and subsequently lime for farming and building mortars. It closed finally in 1962. Two pairs of limekilns remain alongside the Merthyr, Tredegar and Abergavenny Railway and National Cycle Route. Transport Tramroads and railways Clydach Railroad This early railroad was constructed during 1793–4 by the engineer John Dadford. It linked Wain Dew colliery at Beaufort with Glangrwyne Forge on the banks of the River Usk. An important surviving feature of the railroad is the single-arched bridge of coarse rubble-stone near Maesygwartha which is impressively set above a waterfall (at OS grid ref SO 230138). A tramroad linked into the Clydach Ironworks from the Clydach Railroad by means of a cast-iron bridge. Constructed by Smart in 1824, it is one of the earliest in the world. Llam-march Tramroad Engineered by Thomas Dadford in 1793-4, this tramroad (also sometimes referred to as the Llam-march Railroad) to link the Clydach ironworks with the coal mines and iron ore deposits at Gellifelen and Llam-march. There is a single-arched stone bridge