It’s easy to see how secret societies, with their clandestine meeting houses and shadowy initiation rituals, have captured the imaginations of those of us on the outside.

Let’s peek into the windows of mysterious clubs, from not-so-secret societies like the Freemasons to lesser-known groups like the Bullingdon Club.

1. The Bohemian Club

Founded in 1872, the Bohemian Club is an exclusive, invite-only club intended for men—and only men—who consider themselves devoted to the arts. The club’s motto is “Weaving Spiders Come Not Here,” which is supposed to remind members to leave politics and business talk at the door. Whether they truly do that is a matter of debate: It’s rumored that in 1967 Reagan and Nixon discussed the upcoming Republican primaries at Bohemian Grove.

Membership in the Bohemian Club has its perks; the most coveted is perhaps the yearly retreat in Sonoma, where members fly in over the course of two weeks to spend time at the 2700-acre Bohemian Grove to attend various ceremonies, rituals, and networking opportunities.

The Bohemian Grove is made up of over 100 different camps, with names like the Hillbillies, Mandalay, Lost Angels, Cave Man, and Owl’s Nest. In addition to Ronald Reagan and Richard Nixon, other famous faces who have been Grove members over the ages include George H.W. Bush, Clint Eastwood, Mark Twain, and Jack London. Walter Cronkite was also a member; at one point he provided the voice for the club’s massive owl statue that “spoke” to members during opening ceremonies.

If you think all of these people and events sound a little posh, you’re not alone: After a visit to the club in 1882, Oscar Wilde noted, “I've never seen so many well-dressed, well-fed, business-like-looking Bohemians in the whole course of my life.”

2. Belizean Grove

Since the Bohemian Club has been notoriously all-male since its inception, an enclave of powerful women started their own annual retreat in 2001. Called Belizean Grove, this group is mostly made up of accomplished women in their fifties and sixties who turn to each other for the type of advice and networking that only those at the top of the ladder can apparently give.

The group is highly exclusive—it has just 331 members. Though a current list is hard to come by, according to The New York Times, past Grovers have included Supreme Court Justice Sonia Sotomayor (who stepped down from the club before taking her seat on the nation’s highest court) as well as CEOs and high-ranking executives at companies like Nasdaq, Procter and Gamble, Goldman Sachs, and Nordstrom. Every January or February, these illustrious ladies attend a four-day retreat to escape the stress of their day jobs and make cross-industry connections.

Over the years, Belizean Grove has added charters to include younger generations as well. There’s TARA, which stands for Today’s Already Rising Achievers, an offshoot that admits women in their thirties and forties who are rising fast. There’s also Nyomi, specified only as “the youngest cohort of the Belizean Grove,” women who are “already amazingly successful contributors to a greater good.”

3. Skull & Bones

Some well-connected folks claim memberships in multiple secret societies—George H.W. Bush, for example, was a member of The Bohemian Club and Skull & Bones, the Yale student organization that counts John Kerry, William Howard Taft, Time founder Henry Luce, and basically every guy in the Bush family as members.

The society was co-founded in 1832 by Alphonso Taft—President Taft’s father—and William Russell, a college junior who supposedly learned a lot about secret societies when he was studying abroad in Germany. Russell returned to the U.S. determined to start his own group and approached Taft, who happily co-signed.

While the club itself is famous, little is known about what actually goes on behind the doors of its headquarters, known as the Tomb. Leaked stories that may or may not be true include a hazing ritual where members lie naked in a coffin and talk about their sexual exploits. There’s also the disturbing accusation that the society stole the skull of Apache warrior Geronimo in 1918 and placed it on display in their headquarters.

Although Skull & Bones is arguably the most famous society in New Haven, it’s certainly not the only one: Yale’s roster of cloak-and-dagger clubs includes Scroll & Key, Wolf’s Head, Book & Snake, and The Elizabethan Club.

4. The Explorer’s Club

The Explorer’s Club is less about who you are and more about where you’ve been. It’s not just for people with a sense of adventure, but those who have actual scientific or geographic achievements under their belts—think Edmund Hillary summiting Everest or Ernest Shackleton’s Antarctic expeditions.

The club’s New York City headquarters is stuffed with interesting artifacts, like the sleigh from Robert Peary’s 1909 North Pole expedition, the mini Explorer’s Club flag that Neil Armstrong and Buzz Aldrin carried with them to the moon, and, of course, a stuffed whale penis. Members must apply to take an official flag with them on expeditions—one such flag has been to both the highest point and lowest point on earth.

In addition to their achievements, the Explorer’s Club is also known for eating extremely exotic meals at their annual dinner. It was long rumored that in 1951, they ate a 250,000-year-old Woolly Mammoth. DNA testing later revealed that it was actually a turtle.

5. The Independent Order of Odd Fellows

The stated purpose of the Independent Order of Odd Fellows really isn’t odd at all. It’s to help the community, work toward unity and peace, and promote friendship. The Order traces its roots back to 18th century England, where men who worked “odd” jobs with no guild or union banded together. The OOF made its way across the pond and was granted a charter in 1820. Eventually, there was a split in the movement, creating the Independent Order of Odd Fellows.

Despite their good community works, in recent years, the IOOF has perhaps become best known for the trail of skeletons it has left across the U.S. As the organization fell out of fashion, their lodges closed and the buildings were abandoned or sold. When new owners began renovations, they often made the alarming discovery that a skeleton or two had been left behind. Sometimes these were plaster skeletons, no more illicit than Halloween decorations. But sometimes they were the real deal, the remnants of an initiation ritual meant to remind members of their own mortality. As part of the ritual, blindfolded and sometimes chained participants were led through darkened rooms. When they stopped and the blindfold was removed, initiates found themselves eye-to-eye with a real skeleton. It’s thought that some bones were obtained through medical catalogs, but others may have come from graverobbing.

6. The Illuminati

Yes, the Illuminati are real—but probably not in the way you think. At least not as far as we know. Let’s talk about the things we do know: the facts. The Order of the Illuminati was founded in 1776 in Bavaria, by a professor named Adam Weishaupt. Weishaupt’s goal was to encourage open debate and free speech among members and ultimately decrease religious influences on society. He first opened up membership to a handful of his law students, but the idea spread like wildfire, and soon there was a network of more than 2000 members across what is now Germany, France, Hungary, Italy and Poland. The Bavarian Illuminati membership was very young: It's said they initially didn’t trust anyone over the age of 30.

The society existed for a decade before the government shut the group down and exiled Weishaupt. But did the Illuminati really cease to exist? That’s been the debate ever since. By 1797, the first conspiracy theory had sprouted up. Physicist John Robison alleged that the Illuminati had simply joined the Freemasons and continued their teachings. The same year, Augustin Barruel theorized that the Illuminati had masterminded the French Revolution. Illuminati panic even spread to the U.S., where Thomas Jefferson was accused of being a member. (He wasn’t … or was he?)

7. The Bullingdon Club

The Bullingdon Club is a society at Oxford University that was founded in 1780 as a hunting and cricket club, but it quickly became known for its debauchery. In fact, the future King Edward VIII had to leave Bullingdon after his mother, Queen Mary, heard that things were getting a little too rowdy. The club was so infamous that Evelyn Waugh wrote about them in his 1928 novel Decline and Fall, thinly disguised as the “Bollinger Club.”

Only a handful of Oxford students are tapped every year; those who make the cut wake up to their rooms being destroyed. Former UK Prime Minister and Bullingdon Club member David Cameron recalled finding “a group of people making a terrible racket, with one of them standing on the legs of an upended table, using a golf club to smash bottles as they were thrown at him.” Former Prime Minister Boris Johnson was a member during Cameron’s Bullingdon tenure as well.

The society is still going as a supper club today, perhaps toned down in its antics, although its past reputation precedes it.

8. The Freemasons

The largest and least-secret secret society of them all, the Freemasons are said to trace their origins to an actual guild founded in the Middle Ages that supported—you guessed it—masons. Stoneworkers had a tendency to travel for their jobs, so they were often more worldly than others in their hometowns. Over time, when the masons gathered, they talked more about government and world events than they did their actual trade. And over time, they began accepting members who weren’t even in the profession, which also served the purpose of boosting its coffers with a wave of new membership dues. Masons are a fraternity, so it’s male only, but women who are relatives of a Mason can join the affiliate Order of the Eastern Star.

Famous Freemasons? The list is long: George Washington, Mozart, FDR, Houdini, Winston Churchill, Count Basie, Medgar Evers, Davy Crockett, Buzz Aldrin, Oscar Wilde, Charles Lindbergh, Thurgood Marshall—and that’s just to name a few. There are so many important Masons that it’s easy to see why there are conspiracy theories about Masons controlling the world from behind closed doors. According to some insiders, they’re really just doing charity work, handling lodge financials and logistics, and playing cards.

This story was adapted from an episode of The List Show on YouTube. Make sure to subscribe for new videos every Wednesday.

This article was originally published on www.mentalfloss.com as The Real Stories Behind 8 Secret Societies.