The mission at San Juan Bautistia is an extension of the historic state park, though they are owned and operated by different entities. The mission is one of 21 missions that were built along the Royal Road, or El Camino Real, which connected the missions and helped the Spanish spread Christianity to the populations that lived along the California coast. You can still see a small section of the road just outside of the mission.
Built in 1797, Mission San Juan Bautistia is the only mission to continually stay in operation since it was built. As you tour the mission, it's a good idea to keep in mind that people still come here to worship. Touring this building is like traveling back in time. The mission has done a great job at keeping the building authentic and well preserved.
The museum is full of historical artifacts, including memorabilia from the 1958 movie Vertigo that was filmed here. You'll also find a chapel, an old graveyard, and a nice garden in the courtyard to sit and relax for a short while.