1. Alcatraz Island
Alcatraz sits 1.25 miles offshore in San Francisco Bay, and the ferry ride from Pier 33 takes about 15 minutes. The island operated as a federal penitentiary from 1934 to 1963, holding inmates like Al Capone and the "Birdman" Robert Stroud. The strong currents and ice-cold water made escape nearly impossible, which gave the prison its fearsome reputation. Today, nearly 1.4 million people visit annually, and the audio tour through the main cellhouse is one of the best-produced self-guided tours you'll find anywhere. The island is more than just a prison. Before the penitentiary, it was a military fortification and lighthouse. The lighthouse, dating to 1854, is the oldest operating one on the West Coast. After the prison closed, Native American activists occupied the island for 19 months starting in 1969. You can still see their graffiti on the water tower and several buildings. The gardens, tended by inmates' families decades ago, have been restored and bloom year-round. Walking the island takes 2 to 3 hours if you explore beyond the cellhouse. Getting tickets is the hard part. Alcatraz City Cruises runs the ferries, and tours sell out days or even weeks in advance during summer. Night tours run on select evenings and are worth the premium.