The Golden Age of Hollywood began in the late 1920's with the rise of the great studios such as the vertically-integrated Big 5 of Fox, Paramount, Warner, MGM, RKO, and the Little 3 of United Artists, Universal, Columbia. These studios were dominated by powerful moguls and celebrity stars of the Aquarian Age, developed the standardized production of 52 films per year following the rules of the Classic Narrative Style, adopted the technology of the sound revolution, and artificial lighting, imposed an exhibition system of block booking on theaters led by the great movie palaces. Studios responded to social change by creating new genres such as the gangster film in the first Golden Age of the early Depression Era and the G-Man film in the Conservative Era of the later depression, a second Golden Era. The Golden Age ended in the late 1940s with the postwar crisis of studio breakup, declining attendance, the challenges by sports stadiums, shopping centers and television and radio.