网页2024年9月9日 · Alameda, California. Alameda, city, Alameda county, California, U.S. It lies on a 6.5-mile- (11-km-) long by 1-mile- (1.6-km-) wide island in San Francisco Bay, across the Oakland Harbor Channel from Oakland, with which it is connected by bridges and underground tunnels. The site was originally a peninsula that …