Nob Hill is a neighborhood in San Francisco, California, centered on the intersection of California Street and Powell Street. It is one of San Francisco's 44 hills, and one of its original "Seven Hills." Prior to the 1850s, Nob Hill was called California Hill (after California Street, which climbs its steep eastern face). It was renamed after the Central Pacific Railroad's Big Four — called the Nobs — built mansions there. The slang term "nob" means rich or wealthy (a shortened version of the word nobility).