It preserves a significant concentration of buildings dating to California's period of Spanish and Mexican control.

It was well sited for its intended purpose, the conversion of area Native Americans to Roman Catholicism, and was highly successful.

On the southwest side of the plaza stands the adobe of interim Governor José Antonio Castro, one of the most important figures in California's Mexican period between 1835 and 1846.

Built 1839–41, it is an architecturally important example of the Monterey Colonial style, and now functions as a museum within the state park.

[3] One block southeast of the park is the Juan de Anza House, an adobe whose construction predates the rise of the Monterey Colonial style.