San Luis Obispo Octagon Barn, Historical barn in San Luis Obispo County, United States.

The San Luis Obispo Octagon Barn is an eight-sided structure with a central cupola that rises above its wooden floor made of redwood timbers. The building contains stalls and storage areas typical of early 20th-century dairy operations.

Henri LaFranchi, John Damaso and an unidentified "milk farmer" built the barn in 1906. Antonio Stornetta leased it for his Santa Fe Dairy until 1917, not as owner. In 1920 Joaquin and Josephine Pereira, with Eleanor and Manuel Garcia, bought the property for their Home Dairy, which had a pasteurization and bottling plant at 719 Higuera Street. Dairy operations continued into the 1950s.

The Pereira-Garcia families, first- and second-generation Portuguese Americans, ran the Home Dairy here after 1920, following the Italian-Swiss who preceded them in the county's dairy business. Their milk was pasteurized and bottled at 719 Higuera Street and delivered daily across San Luis Obispo. The barn is one of only two octagonal barns left in California.

The barn stands at 4400 Octagon Way on South Higuera, visible from US 101 at the southern entrance to San Luis Obispo. The Bob Jones City-to-Sea bicycle trail begins here and runs to Avila Beach. Parking for over 100 cars is planned on site, and the grounds are being landscaped with hundreds of trees.

The barn is one of only two octagonal barns left in California. Its eight-sided plan approached a circle, cutting the amount of building material needed for a dairy barn. It was listed on the National Register of Historic Places in December 2013.