Oak Ridge straddles the boundary of Anderson and Roane Counties in East Tennessee, west of the city of Knoxville. The city came into existence in 1943 as a "secret city," established under the Manhattan Project for technology development and production of materials for nuclear weapons. In the years following World War II, the city opened its doors to the world and Manhattan Project facilities were converted to other federal government purposes. Today, the extensive energy research and development conducted by private and public agencies make the city one of the world's great research centers. Oak Ridge's best-known institution is the Oak Ridge National Laboratory, one of the U.S. Department of Energy's multipurpose research laboratories conducting research and development in a wide range of scientific and technical areas.