2. Big Pit: National Coal MuseumBlaenavon Big Pit National Coal Museum is an industrial heritage museum in Blaenavon, Torfaen, South Wales. A working coal mine from 1880 to 1980, it was opened to the public in 1983 under the auspices of the National Museum of Wales. The site is dedicated to operational preservation of the Welsh heritage of coal mining, which took place during the Industrial revolution. Located adjacent to the preserved Pontypool and Blaenavon Railway, Big Pit is part of the Blaenavon Industrial Landscape, a World Heritage Site, and an Anchor Point of the European Route of Industrial Heritage. From Wikipedia, the free encyclopedia.