In 1942, as part of the Manhattan Project, the U.S. government acquired 70,000 acres of land in Eastern Tennessee and established a secret town called Oak Ridge. The name chosen to keep outside speculation to a minimum, because Oak Ridge served a vital role for the development of the atomic bomb. The massive complex of massive factories, administrative buildings and every other place a normal town needs to function, was developed for the sole purpose of separating uranium for the Manhattan Project. The completely planned community was designed by the architecture firm of Skidmore, Owings and Merrill, and had a population of more than 70,000 people. Due to the sensitive nature of the work at Oak Ridge, the entire town was fenced in with armed guards and the entire place — much like the Manhattan Project in general — was a secret of the highest concern.
My grandfather worked at the Oak Ridge facility during the war, and when he went home to the farm, he never discussed anything work-related with his family. Read more about how Oak Ridge was born at A Continuous Lean. Link -via Metafilter
They took their secretiveness very seriously. Even now I think you need Q-clearance to work in many of the plants. And, back in my high school years I think the ratio of PhD to non-PhD was the highest in the nation.
It's still a beautiful little city and the guard shacks are still present at you enter and leave town on the Oak Ridge Turnpike.