Big Pit National Coal Museum () is an industrial heritage museum in Blaenavon, Torfaen, Wales. A working coal mine from 1880 to 1980, it was opened to the public in 1983 as a charitable trust called the Big Pit (Blaenavon) Trust. By 1 February 2001 Big Pit Coal Museum was incorporated into the National Museum and Galleries of Wales as the National Mining 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. History of the working pit Big Pit was originally an iron mine, driven into the side of the mountain not far from the surface due to the shallow iron deposits, the level is called Engine Pit Level and can still be seen on the bridge connecting Blaenavon and Garn Rd at . The Iron Workings are above the Big Pit coal workings, for some time Engine Pit Level was used as an emergency exit for Big Pit whilst it was working, now the River Arch Level is the escape route. Engine Pit Level was driven around 1810 by hand due to dynamite being invented 5 decades later, there are no known records of the iron mine. There are a few pictures online showing the interior of the Engine Level from the 1960s when miners from Big Pit explored the level, finding an old flange-less wheeled dram inside, now at a museum. There was also a known Iron Workings shaft, Engine Pit Shaft which existed, information and location of this shaft can be on Industrial Gwent. The Big Pit is part of a network of coal workings established in Blaenavon in the first half of the nineteenth century by the Blaenavon Iron and Coal Company as part of the development of the Blaenavon Ironworks, which means it has some of the oldest large scale industrial coal mining developments in the South Wales Coalfield. The mine was the most important of all the collieries located in Blaenavon. The nearby Coity Pit is shown in reports in the 1850s, consisting of two shafts in diameter which were difficult to pump out. Historians disagree about when the Big Pit was first in consistent operation,