Clydach Gorge

It runs for 5.6 kilometres (3.5 mi) from the vicinity of Brynmawr in Blaenau Gwent eastwards and northeastwards to Gilwern in Monmouthshire.

[citation needed] It has long been an important transport corridor between Abergavenny and the lowlands of Monmouthshire and the northeastern quarter of the South Wales Coalfield.

The Gorge is included within the Brecon Beacons National Park and is a tourist destination in its own right, with facilities including a picnic site, waymarked footpaths, the National Cycle Network and car parking alongside the River Clydach, easily reached from the Heads of the Valleys Road.

[3] By 1841 the works was responsible for the employment of more than 1350 people though many of this number were associated with obtaining iron ore, limestone and coal further up the valley.

[8] 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.

[9] Llanelly Quarry supplied the Clydach Ironworks with limestone, and subsequently lime for farming and building mortars.

Two pairs of limekilns remain alongside the Merthyr, Tredegar and Abergavenny Railway and National Cycle Route.

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).

The routing of the line through the gorge was a considerable engineering challenge requiring the digging of several tunnels and the construction of an impressive curving viaduct across the ravine of the Nant Dyar.

Achieving a consistent gradient of 1 in 20 for a distance of 4 kilometres (2.5 mi) it climbs 210 metres (690 ft) from Gilwern to Brynmawr.

[18] The entire Clydach Gorge falls within the Brecon Beacons National Park designated in 1957 in order that its landscapes be protected and for the quiet enjoyment of them by the public.

There are, in addition, numerous scheduled ancient monuments within the gorge, representing a history of human occupation from the Iron Age to the Industrial Revolution.