The Machines That Made the "Little Boy" Bomb

In 1942, the U.S. government built Clinton Engineer Works (now known as Oak Ridge, a secret city just outside of Knoxville, Tenn. Oak Ridge was part of the Manhattan Project and housed the 1,152 calutrons that produced the 50 kilograms of uranium needed to create the atomic bomb dropped on Hiroshima ("Little Boy"). For the first time, 600 visitors were allowed to see the calutrons during the June 2005 Secret City Festival.