[2] The site is dedicated to operational preservation of the Welsh heritage of coal mining, which took place during the Industrial Revolution.

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.

[4] The nearby Coity Pit is shown in reports in the 1850s,[3] consisting of two shafts 9 feet (2.7 m) in diameter which were difficult to pump out.

[5] In 1939, pithead baths were installed at the mine; it meant miners no longer needed to walk home dirty and wet, risking illness.

[4][c] During the Second World War, surface extraction of coal began at Blaenavon in November 1941 using equipment and skilled men from the Canadian Army.

[citation needed] By 1970 the workforce numbered only 494, as operations had focused solely on the Garw seam, with a maximum thickness of only 30 inches (760 mm).

The NCB paid for the line to be re-extended to Waunavon in the early 1970s, where the drift mine developments accessed the refurbished former Black Lion coal washery.

The Powder House,[22] Saw mill[23] Office[24] and the Electrical Workshop,[25] were each given Grade II listed building status on 2 September 1995.

[7] A substantial Heritage Lottery Fund grant of more than £5 million was awarded in January 2000 which paid for a significant upgrade of the visitor facilities.

[citation needed] Intentionally preserved as an operational attraction, the site was redeveloped in 2003, with design work from TACP/Brooke Millar Partnership.

This is to ensure that all visitors have the highest chances of seeing where their tour guide is, due to the pitch black conditions when there is no light.

The museum features a range of above ground attractions including a winding house, saw mill, pithead, baths.

[34] In 2000, the Blaenavon industrial area, including Big Pit National Coal Museum, was named a World Heritage Site by UNESCO.

[5] Visitors wear a plastic hard hat, safety lamp, and a battery on a waist belt which weighs 5 kilograms (11 lb).

Visitors must also carry on their belt a rebreather, which in case of emergency will filter foul air for approximately one hour, giving a chance for survival and escape.

[39] Before taking the 50 minute underground tour 90 metres (300 ft) below ground, contraband must be surrendered, such as anything containing a dry cell battery from watches to mobile phones.

[39] The cover of the Manic Street Preachers album National Treasures – The Complete Singles shows the Big Pit winding tower.

[40] Historian Gwyn A. Williams used the Big Pit as a setting for one of his programmes in his Channel 4 series The Dragon Has Two Tongues, broadcast in January 1985 - near the end of the miners' strike and as men were returning to work.