The Pereira Octagon Barn of San Luis Obispo is a historic structure located on the southern outskirts of San Luis Obispo, California. It was built in 1906 by Henri LaFranchi, a young Italian-Swiss immigrant and the owner of a small meat market, John Damaso, an Azorean immigrant and a carpenter by trade, and a third, unknown man identified only as a “milk farmer.” Since there were no other octagonal barns in the area, the builders may have worked from patterns of octagonal construction in farm journals or catalogs.
The first user of the barn was Italian-Swiss immigrant Antonio Stornetta, who leased the barn for his Santa Fe Dairy operation until 1917. Joaquin and Josephine Pereira, with Josephine's sister Eleanor and her husband Manuel Garcia, purchased the property in 1920 and made it part of an adjoining dairy operation in the Los Osos Valley.
Wikipedia https://en.wikipedia.org/wiki/San_Luis_Obispo_Octagon_Barn
Coordinates 35°14'12.735" N -120°40'46.354" E