This park is adjacent to one of California's 21 Franciscan missions. The location was once the largest town in central California and the hub of travel between northern and central California. The mission is owned and operated by the Catholic Church and has been in continuous use since July 1, 1812.

The park site includes several structures built in the 1800s. These include the Plaza Hotel, Plaza Hall and stable, blacksmith shop, granary, jail and the Castro Breen adobe. Exhibits show California life of the Mission, Mexican and early American periods.