The historic Simi Adobe–Strathearn House served as the headquarters of Rancho Simi, also known as Rancho San José de Nuestra Senora de Altagracia y Simi, one of the land grants in Alta California by the Spanish government. The name derives from Shimiji, the name of the Chumash village here before the Spanish. Rancho Simi was the earliest Spanish colonial land grant within Ventura and Santa Barbara Counties. At 113,000 acres, Rancho Simi was one of the state's largest land grants.