These are the UK's ten most incredible tourist attractions that you should visit if you're interested in secret wartime bunkers, ancient cave networks, and other manmade and man-used underground places.
10. Chislehurst Caves, Kent
Today Chislehurst Caves are a tourist attraction and although they are called caves, they are technically a mine as they are entirely manmade. In total there is over 22 miles of intersecting tunnels that were dug out in the mid-13th to early-19th centuries as a source of flint and lime-burning chalk.
9. The Hellfire Caves, West Wycombe
Like Chislehurst Caves, the Hellfire Caves are a manmade network of chalk mines, which extend a quarter of a mile underground near the village of West Wycombe. The caves have a past of satanic rituals, worship and sacrifice, making them a fascinating place to visit. The caves were once the meeting place for the Hellfire Club a group of influential members of society including politicians. It's believed they practiced black magic and engaged in orgies. They're probably the smallest attraction on the list, but one of the most unique.
8. Wookey Hole Caves, Somerset
The famous show caves in Somerset is a vast network of impressive limestone chambers. Guests are taken on a guided tour through the atmospheric and well lit caves and given a fascinating account of their geological highlights and their uses through the years.
7. Scotland's Secret Bunker
One of the UK's biggest and most secret bunkers was hidden in the small Scottish town of Anstruther, near Troywood in Fife. This regional government hideout was hidden beneath an innocent-looking Scottish farmhouse. The bunker which was kept secret for over 50 years and in use until 1993. It would have been occupied by UK Armed Forces and civil servants in preparation for a potential nuclear emergency. Following the Cold War, the bunker was unused for a decade before being reopened, this time to the public as a museum in 1994. It is now known as Scotland's Secret Bunker.
6. Edinburgh Vaults, Scotland
The Edinburgh Vaults are a network of eerie chambers which are formed in the arches of the South Bridge in Edinburgh. Due to the city's growing population, the 120 rooms or 'vaults' beneath the bridge were put to use to house taverns, workshops for cobblers and other tradesmen in 1788. The vaults were damp with poor air quality and conditions were grim, which resulted in businesses leaving. This meant that the dank caverns were overtaken by Edinburgh's poorest citizens, the homeless and criminals, who carried out activities such as illegal gambling, whisky distillery and even bodysnatching. Eventually the vaults were filled in and forgotten about, until they were rediscovered in the 1980s and eventually opened as a tourist attraction.
5. Big Pit National Coal Museum, Wales
Not only is the Big Pit an educational insight into Britain's coal mining history, the former working coal mine in South Wales is also completely free to visit. The mine operated from 1880 to 1980, and was opened to the public in 1983.
4. Cabinet War Rooms, London
One of London's most famous tourist attractions. Situated under Whitehall in the centre of the Capital, the Cabinet War Rooms was Prime Minster, Winston Churchill's hideaway during the Second World War, built in a reinforced basement beneath the treasury building. The facility was abandoned in 1945 as the war came to an end, but the site stayed in the hands of the government who maintained it and protected it for its historic value. In the early 80s, with the backing of Prime Minister Margaret Thatcher, the Imperial War Museum took over caring for the bunker and the Cabinet War Rooms were opened to the public. Proving a popular tourist attraction, the bunker has been maintained and improved, it underwent major development works in 2005 and in 2012 had a facelift in the form of a new entrance.
3. Hack Green Nuclear Bunker, Cheshire
Now maintained as a museum and packed full of wartime and military artefacts, the reinforced concrete bunker built at Hack Green was part of the ROTOR project during the Cold War. After being abandoned for some years, the Home Office took it over and converted the bunker to Regional Government Headquarters which remained in use until 1992.
2. London Post Office Railway
Mail Rail is the newest attraction on our list. The narrow gauge, driverless underground railway has been hidden beneath the streets of London since 1927, but closed in 2003. Its purpose was to move mail between sorting offices without having to take congested surface routes. Today it has been opened to the public and visitors are able to take a 15 minute ride on the underground mail train.
1. Kelvedon Hatch, Essex
Not far from Brentwood is Kelvedon Hatch, a huge underground bunker, hidden beneath an innocent looking cottage in the Essex countryside.
The bunker is spread over three floors and is accessible through a 100 meter long access tunnel from an ordinary looking cottage, on closer inspection it's clear the cottage is far from normal, built with thick concrete walls and windows protected by steel shutters. A huge broadcast tower above the hideout marks its location.
Kelvedon Hatch was built in the early 50s by the Air Ministry on land requisitioned from a local farmer. It was put in to operation in 1953 as an RAF ROTOR station, one of many bunkers across the country whose role was to provide complete radar cover for the UK.
In 1992, the threat of the Cold War died down, the bunker was decommissioned and was bought back by the family of the original land owner. Now in private hands, the bunker has been restored and is run as the "Secret Nuclear Bunker" museum.