Abandoned Spy Stations & Tunnels

Germany - A Cold War relic lies abandoned on top of a mountain made of rubble, built over a Nazi college that couldn't be destroyed after the end of World War II. 

Click to enlarge.

The gates of the former US spy station are locked and secure; its perimeter sealed by an uncompromising high fence, an angry crisscross mesh of wires that clearly imply: “Eintritt Verboten!”
Welcome to Teufelsberg, literally “Devil's Mountain,” a hill reaching 114.7 meters above sea-level, made from an estimated 12 million cubic meters of war rubble (apparently about 400,000 bombed houses) pushed together in the north of the Grunewald forest in West Berlin. (more) (video)
 
Canada - Driving aimlessly along country roads you never know what you will come across, and earlier this week while looking for visiting snowy owls, we came across something that seemed worthy of investigation. A lone government sign in a farmer’s field north of Richmond, simply labeled “Area 9” with a locked gate to a long abandoned road...

“The site was part of a Cold War Project for over the horizon radio detection finding, likely used to listen to embassy communications. It consisted of a very large array of receiver antennas laid out in a NS and EW axis. The array was almost a mile long and antennae wiring fed back to a building south along the lane-way.” (more)

...and David W. Brown chronicles... 
5 Spy Tunnels From Around the World