Under the 48-year leadership (1924-1972) of director J. Edgar Hoover, the FBI became the supreme federal authority in matters of domestic crime. As the principal investigative arm of the Justice Department, the FBI traces its beginnings to 1908, when a permanent force of special agents was placed under the control of the attorney general. Officially known as the J. Edgar Hoover FBI Building, the FBI's fortresslike headquarters building covers a city block and houses nearly 8,000 workers. The bureau's public tour program has been suspended for the foreseeable future.