Atom Age Gatehouse

Oak Ridge, Tennessee

For years the "secret city" of Oak Ridge -- the installation which helped build the Hiroshima A-bomb -- was encircled by 90 square miles of barbed wire. When it finally opened to the world in 1949, three big Cold War gatehouses were built between the town and the surrounding, still-secret uranium plants.

All of the gatehouses were abandoned in 1953; this is the best surviving example. It stood on the road to K-25, a gaseous diffusion facility that at the time was the largest building in the world.

K-25 is gone now, and the road is a public highway. The still-standing main gatehouse has its own parking lot for visitors and a guard tower topped with a powerful searchlight. The interior has been restored with period furniture and some exhibits, but it's owned by the Department of Energy and not usually open to the public. Across the highway is a smaller gatehouse. Both buildings still have their old gun portals and bulletproof glass. Anyone who tried to drive past without permission was expected to be shot.

We were the only tourists when we stopped by, although a hand-written letter of encouragement had been left by a Pokemon Go player. There was also a cautionary sign asking visitors to wipe their feet to control the spread of Kudzu, an enemy that can't be stopped by any gatehouse.