Abersychan was a thriving industrial centre in the 19th and early 20th centuries. Mining began at Cwmbyrgwm Colliery began before 1820 and expanded with the development of the British Ironworks in 1827. The British Ironworks (1827-83) was built to the design of Decimus Burton. There were four furnaces, of which only the bases survive, with coke and calcining ovens. The site is approached through 'Big Arch', an impressive 50-yard, 48ft wide tunnel beneath the Monmouthshire Railway and Canal Company embankment of 1879. The Abersychan Limestone Railway was constructed circa 1826, to transport the raw stone from Cwm Lascarn quarries, to the east of Abersychan, to the British Ironworks. The railway was in use for over 20 years and used an unusual form of rail (wrought iron fish-belly rail) which was unique in South Wales.

RCAHMW, 2012.