The 13-story annex, designed by the El Paso architecture firm Trost & Trost, opened in 1930. The 180-room annex contains a bungalow penthouse that is only accessible from the building's roof. The bungalow contains two bedrooms with private baths, a living room, and a full kitchen. The bungalow was originally used as a private residence by superintendents of the Southern Pacific Railroad, but was later rented to high-profile guests including Jack Dempsey, Bob Hope, and President Lyndon Johnson. In 1979, the hotel manager restored the bungalow to use as his private residence.