RKO Forty Acres was a film studio backlot in the United States, owned by RKO Pictures, located in Culver City, California. Best known as Forty Acres and "the back forty," it was also called "Desilu Culver," the "RKO backlot," and "Pathé 40 Acre Ranch," depending on which studio owned the property at the time. For nearly 50 years it was known for its outdoor full-scale sets, such as Western Street, Atlanta Street, and Main Street and was used in many films and television series.

A backlot is an area behind or adjoining a movie studio containing permanent exterior buildings for outdoor scenes in filmmaking or television productions, or space for temporary set construction.