Parts of the underground working at Big Pit date from the early nineteenth century but the shaft at the present colliery was sunk around 1860 and deepened in 1880. The pit was operated in connection with Blaenavon Ironworks Company until nationalisation in 1947.

Most of the surface buildings are present on the site except the washery which has been demolished. The buildings are exceptional in being the most comprehensive overground and underground layout surviving in Wales; the pit bank and steel headframe date from 1921, the tram circuit and electric winding engine date from 1952, the fan house dates from 1910 and there are also workshops and offices. The baths and canteen were built in 1939 and are a good example of the International Modernist style. Coal production ceased in 1980 and the site is now the Welsh Mining Museum and open to the public with underground access.

RCAHMW, July 2011

Source: A Guide to the Industrial Archaeology of South East Wales, AIA, 2003