The Pacific-Union Club is a private social club located at 1000 California Street in San Francisco, California, at the top of Nob Hill. It was founded in 1889 as a merger of two earlier clubs: the Pacific Club (founded 1852) and the Union Club (founded 1854). The club allows only men to join; women are and always have been excluded as per the club's charter. The clubhouse was built as the home for the silver magnate James Clair Flood. The former Flood Mansion is located in the Nob Hill neighborhood. It was designed by Willis Polk. It is considered the first brownstone constructed west of the Mississippi River.