There are 21 Missions in California. They were constructed by the Spanish and organized by the Friars who wanted to convert the "heathons" (aka the indiginous Indians) into good Christians. They were led by Father Junipero Serra and the first one was in San Diego California. They were established at one-day-apart journeys, but were not built in linier/chonological order.
Nonetheless, La Purisima remains as the best example we have. Throughout California, it is not uncommon to find the mission across the street from a mini-mall. Here, La Purisima is on the outskirts of a town called Lampoke. Lampoke is known for growing flowers and is very rural. Thus, there has not been any encroaching town to take over this beautiful land.
Originally built in 1787 by Friar Fermin Lasuen and is equal distant between San Luis Obispo and Santa Barbara. This one, like all the missions, suffered the ravages of time. During the depression, the national Parks Service along with one of the better government creations was the CCC (the California Conservation Corps). In many cases, engineers, carpenters, stone masons, etc were brought from out of work and given work rebuilding things like the California missions. In the 1930 repair and restoration was begun and by the early 50 was completed. Now, run by the California Parks, all the missions are part museum, part living history depending on the limitations of where the mission is located. This park/mission is the largest historic restoration in the western US.