Beneath the streets of London, there is a vast, mile-long network of tunnels. And while they may be abandoned, they're not like the rest of the entries on this list: They're actually still in peak condition. They were used as community bomb shelters during WWII, and were built with every amenity needed to keep a whole society happy, healthy and entertained for up to five weeks. There are full, functioning restaurants, rec rooms, pool halls, movie theaters and even pubs down there, just waiting to be used.
The aesthetics are all original too, so the design of the residential tunnel areas is still in keeping with '50s sensibilities. If
vault sections stirred something in the crazy isolationist in you, well you'll be happy to know that those things are plenty real, and they're conveniently located right in the heart of London. All utilities -- electricity, water and phone -- still function just fine, because the tunnels have been occupied at various points in history by codebreakers, soldiers, British Secret Service and eventually the BT Group, a European phone company. The last owners put the tunnels up for sale back in 2008, to the tune of $7.4 million dollars. Though they wanted to keep both the entrance:
... and the name of their prospective buyer a secret, rumors say the latter was a man named Simon Woodroff, who we can only assume is a roguish chap living a seemingly devil-may-care playboy lifestyle, yet plagued by grief, anger issues and a rather unhealthy penchant for winged nocturnal rodents.
During the Cold War, Chairman Mao commissioned the largest bomb shelter in the world, right beneath the streets of Beijing, China. It was intended to house six million people, and it was all interconnected. See, he didn't want his citizens to merely survive a nuclear attack -- he actually wanted the city to continue to function, unimpeded, even as radioactive hellfire rained down from above.