LA: Hidden Tunnels
If you want to impress your friends the next time they come to visit, take them to the underground maze of tunnels under Downtown Los Angeles. The tunnels run from Temple and Spring streets to 1st Street and Grand Avenue. Some are actually abandoned subway underpasses but others date back to the Prohibition era.
Source: The 13th Floor
The tunnels were used to supply liquor to some of the devious establishments in the city. Rumor has it that the tunnels were also where mobsters stored bodies and some say that the police used them to transport prisoners. Although many are now mostly closed off, some are still open and even used as film locations.