In a tiny, two-room office located on the fifth floor of the New War Building, General Leslie R. Groves and a handful of staff members oversaw the activities and functions of tens of thousands working on the top-secret Manhattan Project. Groves had selected Washington D.C. as headquarters shortly after being named director of the Project in late September 1942 because it allowed him to keep in contact with the War Department and other government agencies that would prove crucial to the success of the Project. Groves lived in Cleveland Park, though he often spent nights away from home for his travels on the project.
Other DC organizations contributed to the project, including the Carnegie Institute of Washington. Several top Manhattan Project scientists and personnel had homes in the DC area, including Edward Teller and Secretary of War Henry Stimson.