(Video Link)
Built in the 1950s, this bunker in Wiltshire could house and feed 4,000 people for three months. The United Kingdom designed it to house the government if the worst happened during the Cold War. Watch this video tour of its facilities and make an offer. It's up for sale.
Link -via Boing Boing
As of December 2011, nothing has been done, it's not been sold, and all that lovely telephone exchange and stuff is slowly succumbing to dry rot.
The potential for this place is amazing, but the government are just being like a dog in a manger with it.