Vallejo is a city in California's San Francisco Bay Area. It's home to Six Flags Discovery Kingdom, a huge amusement park with high-speed roller coasters. The Vallejo Naval and Historical Museum explores the history of the city and the U.S. naval base at Mare Island. The ornate 1911 Empress Theatre hosts concerts and films. Trail-lined Benicia State Recreation Area covers grassy hillsides and rugged beaches.