For nearly half of the 20th century, most of the world was a chessboard for the Soviet Union and the United States. As the two superpowers jockeyed and jostled for power, their machinations created a very specific sort of construction boom: Bunkers, top-secret tunnels, and conspicuous yet classified communications towers, all over the world.

Today, more than 30 years after the fall of the Berlin Wall, many of these Cold War relics have been bulldozed, given back to nature, or simply abandoned. Others have been converted to community parks or lookout towers. A few are still active and off-limits to the public. You can, however, visit some of these sites that have been carefully preserved or restored—or, in the case of bomb test sites, left as they are—to bear witness to decades of tension, paranoia, and ruthless brinksmanship.