Plans have been revealed for what promises to be London’s most spectacular underground tourist attraction ever: the $268 million transformation of a mile-long series of World War II tunnels into a glitzy immersive experience. So clandestine they were once protected by the UK’s Official Secrets Act, the former spy tunnels are set to be reworked by a team including the architects behind Singapore’s Gardens by the Bay and London’s Battersea Power Station – if it secures planning approval later this fall. The Kingsway Exchange Tunnels, some 40 meters below Chancery Lane tube station in High Holborn, were built in the 1940s to shelter Londoners from the Blitz bombing campaign during World War II. That was the last time they were open to the general public. Their next wartime role was as the home of Britain’s top-secret Special Operations Executive, an offshoot of MI6 and the real-life inspiration for James Bond’s Q Branch. Hotline bling Next they were expanded to become the Kingsway Telephone Exchange, which in the 1950s served as an internal communications exchange during the Cold War. It even hosted the “hot line” which directly connected the leaders of the United States and the USSR. The exchange was home to a heaving network of 5,000 trunk cables and a busy community of 200 workers manning the phone lines. British Telecom took over the site in the 1980s, creating the world’s deepest licensed bar for use by the government staff, complete with a games room containing snooker tables and a tropical fish tank - the height of ‘80s luxury. The technology behind the telephone center became obsolete by the end of the decade and was decommissioned. But now fund manager Angus Murray, CEO of The London Tunnels, wants to bring the history of the tunnel to life for visitors with high-resolution immersive screens, interactive structures, scent-emitting technology and hundreds of pinpoint speakers. Subterranean London “The history of the tunnels, their scale and the location between London’s Holborn and the historic Square Mile, could make these tunnels one of London’s most popular tourist destinations,” Murray said in a statement. The plan is to invest £140 million ($170.5 million) in the restoration work and then another £80 million ($97 million) into all the immersive bells and whistles. With architects Wilkinson-Eyre on board, they certainly have a stellar team assembled for this very ambitious of projects - which far outscales anything else on offer in the city. London’s best developed permanent underground tourist attraction currently is the Churchill War Rooms - located just 12 feet below ground level and a fraction of the 8,000-square-meter space occupied by the Kingsway Exchange Tunnels. London Underground also periodically puts Hidden London tours exploring the city’s abandoned tube stations and tunnels. The tours are always hugely popular and over-subscribed, with tickets snapped up as soon as they’re available. They’re still your best chance of subterranean adventure for a few years yet, however, as the London Tunnels project – if it goes ahead - won’t be welcoming its first awestruck visitors until 2027. It sounds like it could well be worth the wait.