It is worth the short drive north of Paso Robles to San Miguel CA to see the historic Franciscan Mission. Mission San Miguel, named for the Archangel Saint Michael, was founded by Franciscan Father Fermin Francisco de Lasuen in 1797, and was meant to close the gap between Mission San Antonio to the north and Mission San Luis Obispo to the south. You can attend a mass on Sunday or early on weekdays or take a tour at other times.
While in San Miguel, make sure to visit the Rios Caledonian Adobe. The century-old inn and stage stop is located on the old mission trail between San Francisco and Los Angeles and is adjacent to the San Miguel Mission. I enjoyed the preserved buildings and the small museum with period decorated rooms. There is also a piece of the original, concrete, one-lane highway connecting LA to San Francisco that you can see.