Take a documentary tour of London's dark and dank underground tunnels

We've seen the urban spelunkers at Silent UK plumb the depths of London's abandoned mail train. Now they've created Crack the Surface, the first in a series of short films detailing their explorations of London's underground, an experience one spelunker compares to a real-life roleplaying game. » 7/16/11 6:00pm 7/16/11 6:00pm