The park is part of a nationally recognized historic landmark adjacent to California's 15th Spanish era mission. The park and its Plaza represent what was once the "town square" of the largest town in central California and a vital crossroad for travel between northern and southern California. Visitors can gain an appreciation of California's people, from Native Americans through the Spanish and Mexican cultural influences, right up to the American period in the late 19th century.

The park includes several structures built in the 1800s. The four main historic museums are the Plaza Hotel, the Zanetta House/Plaza Hall, the Plaza Stables, and the Castro-Breen Adobe. Many of the interiors are furnished vignettes or colorful and informative exhibits that help create a unique learning environment for people of all ages. The park also features a blacksmith shop, the historic jail, and an early American settler’s cabin.