If you can only do one tour while in San Francisco, make it Alcatraz. Probably the most famous prison in America, if not the world, this was where the worst of the worst criminals were marooned to suffer and freeze in the Bay. The building has barely changed at all from its days as a “grey-bar hotel.” It’s like walking through the past.

A bit of history: In 1775, Juan Manuel Ayala was the first European to set foot on the island. He named it after the many alcatraces, or pelicans that nested here. From the 1850s to 1933, Alcatraz served as a military fortress and prison. In 1934, the government converted the buildings of the military outpost into a maximum-security civilian penitentiary, one of the roughest places to be incarcerated in history. Inmates suffered psychologically and emotionally. The wind howled through the windows, the concrete was chilly and dank, and everything good and right in the world was perennially located at an unreachable distance. Given the sheer cliffs, treacherous tides and currents, and frigid water temperatures, it was believed to be totally escape-proof. Among the famous gangsters who occupied cellblocks A through D were Al Capone; Robert Stroud, the so-called Birdman of Alcatraz (an expert in ornithological diseases); Machine Gun Kelly; and Alvin “Creepy” Karpis, a member of Ma Barker’s gang. It cost a fortune to keep them imprisoned here because all supplies, including water, had to be shipped in. In 1963, after an apparent escape in which no bodies were recovered, the government closed the prison. It moldered abandoned until 1969, when a group of Native Americans chartered a boat to the island and symbolically reclaimed the island for the Indian people. They occupied the island until 1971—the longest occupation of a federal facility by Native Americans to this day—but eventually were forcibly removed by the government. (See www.nps.gov/archive/alcatraz/indian.html for more information on the Native American occupation of Alcatraz.) The next year the island was given over to the National Park Service, natural habitats were restored, and the wildlife that was driven away during the prison years began to return. Today, you can see black-crested night herons and other seabirds here on a trail along the island’s perimeter.

Admission to the island includes a fascinating audio tour, “Doing Time: The Alcatraz Cellhouse Tour,” narrated by actual former convicts, who are less grizzled than you might guess; the main voice pronounces “escape” as “excape,” as someone’s adorable Midwestern grandpa might. Don’t be shy about pausing the recording with the stop button, otherwise it rushes you along a bit too quickly. And don’t be afraid to break away after your first pass through Broadway (the main corridor) so that you can explore the recreation yard. Wear comfortable shoes (the National Park Service notes that there are a lot of hills to climb) and take a heavy sweater or windbreaker, because even when the sun’s out, it’s cold and windy on Alcatraz. Although there is a beverage-and-snack bar on the ferry, the options are limited and expensive; you might want to bring your own snacks for the boat. Only water is allowed on the island.

Note: The excursion to Alcatraz is very popular and space is limited, so purchase tickets as far in advance as possible (up to 90 days) via the Alcatraz Cruises website at www.alcatrazcruises.com. You can also purchase tickets in person by visiting the Hornblower Alcatraz Landing ticket office at Pier 33. The first departure, called the “Early Bird,” leaves at 9am, and ferries depart about every half-hour afterward until 4pm. Two night tours (highly recommended) are also available, offering a more intimate and wonderfully spooky experience.

For those who want to get a closer look at Alcatraz without going ashore, two boat-tour operators offer short circumnavigations of the island.