In 1839, when Mexico ruled Alta California, José Antonio de la Guerra received a land grant of 48,803 acres in the Los Alamos Valley. Don José Antonio was the son of Don José de la Guerra y Ortega who was the commandante of the Santa Barbara Presidio, from 1815 to 1843.

Indians from a rancheria on his Don José Antonio's estate built the large one-story adobe ranchhouse which retains much of its original appearance and is probably the finest surviving example of adobe ranchhouses built during the Mexican period. In its unaltered rural setting, it presents an admirable picture of ranch life in Mexican California.

The golden era of private ranching in California began with the secularization of mission property in the mid l830s. In 1820, when Spain ruled Alta California, there were only fourteen private ranches. By 1830, under Mexican rule, there were forty-seven private ranches. By 1840 there were 249. By 1845 there were 544.

In 1830, about eight hundred Mexicans lived on the forty-seven Alta California ranches. The herds of a typical ranch included 250 to 400 cattle and 80 to 200 horses.

These large ranches were self sustaining economic units. Indians performed the labor, serving as vaqueros, artisans, farm hands and domestic servants. In return they received food, primitive shelter and a limited supply of clothing.

Some Indians lived in the indiada, a cluster of primitive huts built near the adobe ranchhouse. Others lived in small villages called rancherias.

Source: Adapted from the NRHP nomination submitted in 1970.

Rancho Los Alamos is a National Historic Landmark.

The adobe hacienda is on private property. Today the ranch consists of about one hundred acres and the hacienda is not visible from the public right-of-way.

In March of 2017, the property was for sale. A brochure, published by the realtor, contained photographs showing that the hacienda has been well-maintained and little altered.

Historic Adobe Buildings