Vallejo is the largest city in Solano County, California, United States. Vallejo has twice served as the capital of the State of California. The city is home to the Six Flags Discovery Kingdom theme park (formerly Marine World and Marine World Africa USA) ; the now-defunct Mare Island Naval Shipyard; the regional office for Region 5 of the United States Forest Service; the California Maritime Academy; the Vallejo Center campus of Solano Community College; and Touro University, an osteopathic medical college. Vallejo Naval and Historical Museum, Historical Empress Theater and Vallejo Municipal Marina are other places of interest.