For decades, Great Britain’s mysterious tunnel systems have been a source of fascination, and authorities have been conspicuously secretive about them until recently. New documents released by the British Land Registry in 2017 revealed the existence of a network of tunnels under the streets of Britain, with details on 3.5 million land and property titles under the ownership of councils, housing associations, companies, and corporations such as the Post Office, British Telecom, and the Ministry of Defense. Private photographs and documents of the Cabinet’s rooms, built in 1939 and used by His Excellency Sir Winston Churchill, were also released for the first time in 2016. The protected military accommodation is linked by tunnels and elevator shafts. West of London is another covert underground Ministry of Defense site called MoD Corsham, formerly known as Basil Hill Barracks, located between the towns of Corsham and Box, near Bristol. Commissioned in 1955, the enormous 35-acre complex measures more than a kilometer (0.62 miles) long and is 37 meters (121 feet) underground. The underground city housed hospitals, kitchens, launderettes, canteens, and accommodation. An underground lake provided drinking water and an underground power station had enough fuel in store to keep the generators running for up to three months. Heading northeast of London, another famous set of underground tunnels known as the Victoria Tunnel is in Newcastle. Measuring about 3.6 kilometers (2.25 miles) long, its construction took 200 men two years and 10 months to complete. Between 1842 and the 1860s, the Victoria Tunnel was used to transport coal from Spital Tongues Colliery to the banks of the River Tyne for loading onto ships. In 1939, the tunnel was reopened to house 9,000 residents as a shelter from air conflict. Britain’s fascinating underground tunnels are not only historically revealing but also inspirational, telling stories of mystery and times long passed, sparking the imagination and also informing our future.