Cerro Romualdo is a 1,300-foot mountain in San Luis Obispo County, California, and the fifth of the volcanic plugs called the Nine Sisters. Known officially as Romualdo Peak until 1964, it was named for a Chumash man who received the 117-acre Rancho Huerta de Romualdo from Pío Pico, the last Mexican governor of Alta California. The ranch name means Romualdo’s kitchen garden or orchard, and the land was sold to Captain John Wilson in 1846. In the 1890s, stone from the mountain helped build the Southern Pacific Railroad. Today it is state-owned and used by the California National Guard for fitness training at nearby Camp San Luis Obispo.