At 9:40 a.m. on the morning of August 11, 1934, Alcatraz's first group of prisoners—137 in all—arrived at the soon-to-be-infamous prison. For decades, it was known as the site of one of the most unforgiving federal prisons in the country. “Break the rules and you go to prison,” went one anonymous quote. “Break the prison rules and you go to Alcatraz.” But San Francisco Bay’s Alcatraz Island has a history that goes far beyond its infamy as a criminal commune. Check out some facts about its origins, its history-making protest, and signing up for a tour.

1. Alcatraz was a military outpost in the 1850s.

Described by Spanish explorer Juan Manuel de Ayala in 1775, Alcatraz Island is the Americanized name of Isla de los Alcatraces (Island of the Pelicans). Following the end of the Mexican-American War in 1848, California became property of the United States. In the 1850s, the island was earmarked by U.S. forces for a military citadel. Outfitted with more than 100 cannons, it monitored activity in San Francisco Bay to thwart foreign invaders looking to cash in on California's gold rush. (Later, it was used to discourage Confederates from trying to seize control of San Francisco in the Civil War.) That presence led to some federal prisoners being housed on site—a foreshadowing of the general-population prison it would one day become.

2. Alcatraz inmates were forced to build their own prison.

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When the need for armed monitoring of the bay ended, the U.S. Army deconstructed the fortress, leaving only the basement foundation intact. From 1909 to 1911, the military prisoners were put to work building a new structure that would house disciplinary barracks for the West Coast. (That building is the one standing today.) The military transferred ownership of the island to the Department of Justice in 1933, which is when Alcatraz became synonymous with the worst of the worst, housing notorious criminals like Al Capone and George “Machine Gun” Kelly.

3. Life at Alcatraz wasn't always so bad.

Known as the “Rock,” Alcatraz developed a reputation for segregating America’s incorrigibles from the rest of the population. Sometimes, rules dictated that prisoners couldn’t even speak to one another. But conditions inside the prison weren’t as harsh as movies and television would later portray. Inmates often got their own cell, and some even asked to be transferred there because the potential for violent trouble was low. The reason some of the more notorious criminals of the era were sent there was usually due to the facility’s strict routine. Prisoners had little leeway or privileges outside of the four basics: food, shelter, clothing, and medical care. One perk? Hot showers. Inmates got warm water to use for bathing, although it wasn’t for altruistic reasons. A theory has it that if prisoners got used to warm water, they’d freeze up if they ever made an escape attempt in the bay’s frigid conditions.

4. Odds of escaping Alcatraz were slim.

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Many know the story of Frank Morris, John Anglin, and Clarence Anglin, who famously attempted to escape the prison island in 1962 using a raft made out of raincoats. No one knows whether the men made it, but the odds were stacked against them. Of the 36 men who fled from the site in the 29 years it was open (1934 to 1963), 23 were recaptured, six were killed by guards, and two drowned. The remaining five—including Morris and the Anglin brothers—made it to the water and disappeared.

5. Softball was a popular pastime.

Though Alcatraz would never be confused for a country club, inmates still had outlets to pursue physical activities. Softball was the most popular pastime, with prisoners using a diamond in the recreation area. Organized teams played using shorter innings; balls going over the barricades were outs, not home runs. But not every game went smoothly. The teams were integrated, and that occasionally to racial tensions. During one May 20, 1956 game, tempers flared and makeshift knives were pulled before guards could restore order.

6. Alcatraz's prison guards lived on the island with their families.

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Life at Alcatraz wasn’t isolated just for the prisoners. Guards and other prison employees lived on the island in separate housing that was once Civil War barracks. Their kids fished in the bay and passed time in social halls that had pool and bowling. Families often took weekend boat trips to nearby Marin to stock up on groceries and other essentials. While they were forbidden to make contact with inmates, a few made a spectator sport of watching new arrivals come in wearing shackles.

7. Alcatraz was closed in 1963 because it was too expensive to maintain.

Alcatraz didn’t get shuttered over human rights issues or because the prison was too hardcore even for society’s worst. It closed in 1963 for the same reason it was so distinctive: the location. Saltwater continued to erode structures, making the cost of maintaining the buildings excessive. On a day-to-day basis, Alcatraz cost $10.10 per person to maintain in 1950s dollars, three times as much as most other federal prisons. It also needed freshwater brought in by boat at the rate of a million gallons a week.

8. In 1969, a group of college students occupied Alcatraz in protest.

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In 1969, a group of college students stormed the abandoned prison. Their cause: to draw attention to the United States government's policy of terminating tribal sovereignty and relocating Native American residents to cities. Richard Oakes, a student at San Francisco State College, led the occupation, which lasted a total of 19 months. Authorities moved in 1971 when the group—which was 400 strong at its height—had dwindled to just 15 people. During their protest, Richard Nixon reversed the policy in 1970, effectively ending government seizure of Indian lands.

9. Alcatraz is now one of San Francisco's most popular tourist attractions.

Alcatraz Island was converted into a park and made part of the U.S. national park system in 1972. If you want a tour, you can make advance reservations and book a ferry. Once there, an audio tour will take you through the grounds, including the cells of luminaries like Al Capone. More than 1.5 million people visit annually.

10. Alcatraz has literally gone to the birds.

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Without a permanent human infrastructure, Alcatraz Island has slowly been engulfed by nature’s squatters. One of the first sights visitors see is a surplus of Western gulls taking up residence on almost every surface. The park service even offers a tour of the avian life, which includes 5000 birds across nine different species. The population is fitting, since the prison’s most famous inmate is widely considered to the “Birdman of Alcatraz,” Robert Stroud. After being sentenced for murder, Stroud took up ornithology and was considered to be an expert by the time he arrived on the island in 1942.