The Simi Adobe served as headquarters for the Spanish Colonial land grant San Jose de Nuestra Senora de Altagracia y Simi. Santiago Pico was the original grantee in 1795, followed by three of his sons, Francisco Javier, Miguel, and Patricio, to whom the rancho was regranted in 1821. Jose de la Guerra acquired the rancho by purchase in 1842. Members of the De La Guerra family lived here and at the Tapo Adobe in Tapo Canyon until the onset of the American Period. Robert P. and Mary Strathearn used the remaining two adobe rooms for their dining room, kitchen, and breakfast room when they built their wood frame home in 1893. The kitchen was modernized in 1959.