Dedicate the fourth day of your trip to exploring the cultural side of Fountain Valley. Start with a visit to the Heritage Museum, which showcases the history and heritage of the area through exhibits and artifacts. Next, head to the Noguchi Garden, a serene outdoor sculpture garden featuring the works of renowned artist Isamu Noguchi. In the evening, catch a performance at the Orange County Performing Arts Center, where you can enjoy a variety of shows, from theater to ballet.