Secret Underground City For Sale

The UK government had a secret underground complex in Wiltshire called TURNSTILE or Hawthorn, which it declassified in 2004. In 2005, the UK government offered it for sale as surplus. Doesn't sound like there are any buyers yet, which speaks poorly of the Evil Genius population of our times. From a Times article, quoted in the Wikipedia article above:

"The Ministry of Defence is seeking new tenants for a secret underground city, built to shelter the Government in the event of nuclear war, which is now surplus to requirements. The site at Corsham, Wiltshire, is large enough to house 4,000 government personnel. Completed in 1961, it covers hundreds of acres and is connected by ten miles of tunnels. As well as two railway stations and a reservoir, the sunken suburb 120ft (37m) below ground even has a pub."

"Property developers looking for the ultimate place to get away from it all need not apply. The site has a notional value of £5m but there is a catch. It is available only as part of a private finance initiative that involves investing in the military base on the surface above. Already two uses are being considered: a massive data store for City firms or the biggest wine cellar in Europe. More outlandish ideas put forward include a nightclub for rave parties, a 1950s theme park or a reception centre for asylum seekers. The Ministry of Defence (MoD) has ruled out any suggestion of using it to store nuclear waste or providing open public access because of the dangers that still lurk below."

The BBC has an online tour of the complex, including videos, pictures, and an interactive map.