Alcatraz Island is part of the GGNRA (Golden Gate National Recreation Area), which at more than 75,000 acres is one of the largest urban parks in the world. Alcatraz itself is only a small part of this, but due to the location in the middle of San Francisco Bay it is one of the most visible sites.
The only way to get to the island is by a short ferry ride from San Francisco. It is a bit more than a mile offshore and as a result it offers one of the best views of the city at night that I've ever seen.
