Twenty-eight years after the prophet's death, a secret complex code-named Y-12 was built in Bear Creek, and a secret city sprang up — seemingly almost overnight — in the next valley over in the shadow of Black Oak Ridge. Not shown on any maps at the time, Oak Ridge — first called Clinton Engineering Works after the nearby town of Clinton — was born in 1942 during World War II. It was the key facility in the huge effort called the Manhattan Project to build the world's first atomic bomb.