Who doesn’t love a good mystery? What’s more, who doesn’t love a mystery that defies natural or rational explanation? This list comprises some of the most famous and intriguing unsolved mysteries known to man, listed in descending order from number 20 to number 1.

20.) The Babushka Lady

The Babushka Lady is an unknown woman present during the 1963 assassination of President John F. Kennedy. Her nickname arose from the headscarf she wore, similar to scarves worn by elderly Russian women. Wielding a camera and photographing the events in Dallas’s Dealey Plaza, she was spotted by eyewitnesses and has appeared in film accounts of the assassination. Even after most of her surrounding witnesses took cover, she can be seen standing with the camera to her face. Neither she nor the film she may have taken has yet been identified. 

In 1970 a woman named Beverly Oliver came forward and claimed to be the Babushka Woman, though she is generally regarded as a fraud. To this day, no one knows who the Babushka Woman is or why she refused to come forward to offer her evidence.

19.) Chicago Tylenol Poisonings

The Chicago Tylenol Murders were a series of poisoning deaths resulting from drug tampering in the Chicago metropolitan area in 1982. The seven victims had all taken Tylenol-branded capsules that had been laced with potassium cyanide. Police concluded that they were likely looking for a culprit who had acquired bottles of Tylenol from various retail outlets, most likely supermarkets, and drugstores, over a period of several weeks. He or she probably added the cyanide to the capsules, then methodically returned to the stores to place the bottles back on their shelves. In addition to the five bottles that led to the victims’ deaths, three other tampered-with bottles were later discovered.

No suspect was ever charged or convicted. In the years following, there have been additional deaths in subsequent copycat crimes.

18.) The Mary Celeste

One of the greatest navel mysteries of all time is that of the Mary Celeste. Less than a month after the vessel departed on November 7, 1872, it was found adrift with all 11 members missing. The ship was undamaged and loaded with six months worth of food. No sign of foul play was evident in the mysterious disappearances. The only indication of what could have happened is the absence of a lifeboat from the ship’s deck. The most rational explanation offered comes from the 2007 documentary “The True Story of the Mary Celeste,” which claims that a faulty chronometer, rough seas, and a clogged onboard pump could be the reason the ship was abandoned. The fate of the Mary Celeste passengers has never been discovered.

17.) Who Killed J.F.K.?

Conspiracy theories abound when it comes to the assassination of President John F. Kennedy. We will likely never know with certainty if Lee Harvey Oswald, the primary suspect in the November 22, 1963 assassination, is guilty or not since he was killed by night club owner Jack Ruby two days after the assassination. 

Although investigators have all but concluded that Oswald is the culprit, the public suspects dozens of other individuals in the killing of the young president. Many disagree that Oswald could have been a lone wolf. Some conspiracy theorists have attempted to place blame on Lindon B. Johnson, the “mob,” or the CIA, among others. But most of this random theorizing has been quickly debunked and the blame remains pinned on Oswald.

16.) The Georgia Guidestones 

Sometimes referred to as the American Stonehenge, these stones were erected on March 22, 1980, in the remote location of Elbert County, Georgia. Despite being built only a few decades ago, the purpose of them remains mostly unknown. Very little awareness of the Guidestones circulated until around 2005 when the environmental movement gained momentum.

The surface of the 19-foot tall stones is inscribed with “10 commandments” in eight languages—English, Spanish, Swahili, Hindi, Hebrew, Arabic, Traditional Chinese, and Russian. These commandments include environmental messages such as “Maintain humanity under 500,000,000 in perpetual balance with nature,” “Avoid petty laws and useless officials,” “Balance personal rights with social duties,” and “Be not a cancer on the earth — Leave room for nature.”

15.) Marfa Ghost Lights

These unexplained lights have been observed near U.S. Route 67, east of Marfa, Texas. Those who have seen the lights often equate them to be the result of paranormal phenomena, such as ghosts, UFOs, or will-o’-the-wisp. These mysterious orbs suddenly appear above desert foliage at about shoulder height as they pulse with intensity varying from dim to almost blinding, yellow-orange brilliance. They have also been known to dart across the desert, splitting apart and merging together.

Scientific research suggests that most, if not all, are atmospheric reflections of automobile headlights and campfires. But many sightings take place far from the road, possibly too far for highway traffic to be the culprit. 

14.) Dan “D.B.” Cooper Hijacking and Disappearance

On November 24, 1971, a “nondescript” man bought a $20 ticket for Northwest Orient Airlines Flight 305. Shortly after takeoff from Portland, he handed a note to a flight attendant in which he claimed to have a bomb in his briefcase. Cooper demanded four parachutes and $200,000 in $20 bills (worth about $1.2 million in the early 21st century). After the flight landed in Seattle, authorities provided the money and parachutes and Cooper released the 36 passengers on board. However, he forced two pilots, a flight engineer, and a flight attendant to remain on the plane and ordered the pilots to fly under 10,000 feet at a speed slower than 200 knots to Mexico City. Eventually, Cooper lowered the rear steps and jumped out, disappearing forever. 

Many speculated that Cooper—who was outfitted in a business suit, trench coat, and loafers—did not survive. At that altitude, the winds were more than 200 miles (322 km) per hour, and the parachute he used could not be steered, nor did it have a functioning reserve parachute. After years of dead-end leads, investigators received a break in 1980 when a boy found a decaying package containing $5,800 in $20 bills buried along the Columbia River. The serial numbers of the money matched those of the ransom. However, following an extensive search, nothing further was discovered. Although the FBI continued to receive tips, in 2016 the agency officially closed its investigation on the hijacker.

13.) Severed Foot Beach in British Columbia

Since August 2007, 14 human feet have washed ashore near Vancouver, British Columbia. No bodies, no heads, no clothes, just feet, nearly all still clad in sneakers. The most recent, found last May, was in a hiking boot. Canadian authorities have yet to determine how the feet end up here or why, though DNA tests matched one of the severed feet to a man who’d been missing for several months. 

A number of theories have been tossed around, including the possibility of foul play, although experts say ocean currents and decomposition could have naturally separated the feet from their owners. Others speculate some of the remains might belong to four unrecovered victims of a 2005 plane crash off Quadra Island.

12.) The SS Ourang Medan

In June of 1947, multiple ships traversing the trade routes between Sumatra and Malaysia claimed to have picked up a series of SOS distress signals from the Ourang Medan. The morse code was translated to say “All officers including captain are dead, lying in chartroom and bridge. Possibly whole crew dead….I die” before cutting into silence. When a fellow ship came to the crew’s aide, they found all members dead of no rational cause. To add to the grisly scene, many of the corpses bore terrified expressions on their faces, seemingly frozen on at the time of their death. The captain of the rescue ship attempted to tether and tow the Ourang Medan to land, but the Medan exploded and sank before he was able to do so. 

It has been impossible to solve the mystery of this “death ship” since researchers have found that there doesn’t seem to be any official records that it ever existed in the first place.

11.) The Taos Hum

The Taos Hum has been described as a faint droning sound, similar to a diesel engine idling in the distance in a small town in north-central New Mexico. Since the early 1990s, some residents and visitors of Taos have reported hearing the noise, which never stops, interferes with sleep, and is more noticeable at night and indoors. The Hum became so bothersome to Taos residents that in 1993, locals voiced their concern about it to Congress. A public study was conducted to examine what could be going on. Residents were interviewed and various sound detection instruments were placed around the town. It soon became obvious to those investigating that the Hum did indeed exist. However, researchers have been unable to identify a physical or natural source of the noise as no devices are able to pick up/record it.

10.) The City of Atlantis

The tale of Atlantis was first mentioned by the famed ancient Greek philosopher Plato in 360 B.C. There are many theories about where Atlantis was located—in the Mediterranean, off the coast of Spain, even under what is now Antarctica. “Pick a spot on the map, and someone has said that Atlantis was there,” says Charles Orser, curator of history at the New York State Museum in Albany. “Every place you can imagine.” 

Plato claimed that the founders of Atlantis were half god, half human creatures who created a utopian civilization that became a great naval power. Their home was made up of concentric islands separated by wide moats and linked by a canal in the center. The lush islands contained gold, silver, and other precious metals and supported an abundance of rare, exotic wildlife. There was a great capital city on the central island. To this day, the story of the ancient civilization of Atlantis manages to capture the imagination of countless minds, despite the fact that it is very unlikely to be a true place.

9.) The Loch Ness Monster

In July of 1933, a Scottish newspaper reported the story of local residents Mr. and Mrs. Spicer, who claimed to have seen an “extraordinary form of animal” cross the road in front of their car. The Spicer’s described the creature as nearly four feet tall and 25 feet long with a long, “undulating” 12-foot neck. They said the creature sped across the road in the direction of the Loch, presumably to enter it.

From there, the legend of the Loch Ness Monster, or “Nessie,” took off. There have been countless sightings and testimonies passed through word of mouth and published in newspapers. Supposed photographic evidence also exists. Some of the photos have been debunked as hoaxes, but many still believe there could be an unidentified creature living in the Loch.

8.) Jack the Ripper

Jack the Ripper terrorized London in 1888, killing at least five women and mutilating their bodies in a fashion that indicated he had a substantial knowledge of human anatomy. All five killings attributed to Jack the Ripper took place within a mile radius of each other, in or near the Whitechapel district of London’s East End, from August 7 to September 10. The killer allegedly sent a number of letters (some of which were published in London newspapers) to the London Metropolitan Police Service, taunting officers about his gruesome activities and speculating on murders to come. The letters may have been a hoax, but whether they were or not, the nickname “Jack the Ripper” originated from them—and stuck.

The culprit was never captured or identified. He remains one of England’s—and the world’s—most infamous criminals.

 7.) Area 51

Only a select few are allowed to know what’s happening down the closely-monitored Nevada road leading to the infamous Area 51. The forbidden aspect of Area 51 is certainly what makes people want to know what exactly goes on within its grounds. There are the alien conspiracies that galactic visitors are tucked away somewhere inside. A more colorful rumor insists that the 1947 Roswell crash was actually a Soviet aircraft piloted by mutated midgets and the wreckage remains on the grounds of Area 51. Some also speculate that the U.S. government filmed the 1969 moon landing in one of the base’s hangars.

For all the myths and legends, what’s true is that Area 51 is real and still very active. There may not be aliens or a moon landing movie set inside those fences, but something is certainly being cloaked from the public eye.

6.) The Bermuda Triangle 

Despite the lack of evidence that mysterious disappearances occur with greater frequency in the Bermuda Triangle than in any other area of the ocean, this region of the Atlantic has captured the human imagination with unexplained disappearances of ships, planes, and people. Some imaginative thinkers speculate that unknown and mysterious forces—such as extraterrestrials, sea creatures, the influence of the lost continent of Atlantis, and vortices that suck objects into other dimensions—account for the unexplained disappearances. Other more rational explanations say that weather conditions (such as hurricanes) may be to blame. Also, methane gas erupting from ocean sediments and disruptions in geomagnetic lines could tamper with navigation. The Bermuda Triangle has also been under investigation as a place where a magnetic compass sometimes points towards “true” north, as opposed to magnetic north. 

5.) The Dancing Plague of 1518 

The two-month-long Strasbourg Dancing Plague began in July 1518 when a woman known as Frau Troffea stepped into the street and began to silently twist, twirl and shake. She kept up her solo dance for nearly a week, but eventually, some three-dozen others had joined in. By August, the dancing epidemic had claimed as many as 400 victims. With no other explanation for the phenomenon, local physicians blamed it on “hot blood” and suggested the afflicted were dancing their fever away. Other theories formulated since then suggest that the dancers may have been members of a religious cult or that they accidentally ingested ergot, a toxic mold that grows on damp rye and produces spasms and hallucinations. Many dancers eventually collapsed from exhaustion, and some died as a result of strokes and heart attacks. 

The Strasbourg dancing plague might sound like the stuff of legend, but it’s well documented in 16th-century historical records. It’s also not the only known incident of its kind. Similar events have also occurred in Switzerland, Germany, and Holland, though few were as large (or deadly) as the one triggered in 1518.

 4.) The Shroud of Turin

Also called the “Holy Shroud,” this piece of linen is commonly believed to be the burial garment of Jesus Christ. It has been housed in the Cathedral of St. John the Baptist in Turin, Italy since 1578. It seems to portray two faint brownish images of the back and front of a gaunt, sunken-eyed man. The images contain markings that allegedly correspond to the crucifixion wounds of Jesus, including thorn marks on the head, lacerations on the back, bruises on the shoulders, and various stains of what is presumed to be blood.

The Vatican has encouraged scientists to verify the authenticity of the linen. In 1988, small samples of the cloth were sent to three laboratories in different countries to be subjected to carbon-14 dating. All three laboratories concluded that the cloth had been made sometime between 1260 and 1390. However, researchers have recently found that the nature of the blood stain patterns on the Shroud are unlikely to match the flow of the blood stains that would have resulted from Jesus’ injuries. This is only a small strike against the cloth’s authenticity, but it certainly adds to the mystery.

3.) JonBenet Ramsey’s Murder

On December 26, 1996, John Ramsey, a wealthy software executive, found his 6-year-old daughter and upcoming beauty queen, JonBenet, dead in the basement of his Boulder, Colorado home. Eight hours prior, his wife Patsy had found a ransom note demanding $118,000 for their daughter’s safe return. 

Investigators failed to conduct a proper search of the house and even allowed friends of the family to walk in and out of the crime scene as the family and police waited for a ransom call.

While John’s two adult children from a previous marriage were cleared of the murder early on, suspicion remained pinned on the three people who were the only ones known to be home when JonBenet was killed — her 9-year-old brother and her parents. Years after the murder, JonBenet’s brother continued to be questioned by a grand jury but was never charged. And in July 2008, prosecutors were finally able to conclude that John and Patsy were not responsible for their daughter’s murder. Two years earlier, Patsy died of ovarian cancer and John Mark Karr was arrested after he admitted to killing JonBenet. However, the case against Karr was dropped two weeks after the man’s confession when DNA tests showed he could not have been at the crime scene.

2.) The Zodiac Killer

The Zodiac Killer is an unidentified American serial killer believed to have murdered at least six people and injured two others in northern California between 1966 and 1969. The murders were the subject of intense investigation and media coverage, mostly due to the killer’s taunting letters and phone calls in which he explained his decision to kill. These letters demonstrated great interest in astrological symbolism. One letter read, in part: “I like killing people because it is so much fun it is more fun than killing wild game in the forest because man is the most dangerous animal of all to kill something gives me the most thrilling experience…when I die I will be reborn in paradise and those I have killed will become my slaves.” 

Some people following the case believe the Zodiac Killer remained active through the 1980s, murdering dozens of more people. During the 1990s, several investigators attempted to identify the killer as Arthur Leigh Allen of Vallejo, California, though these claims have never been substantiated.

1.) Stonehenge

Perhaps the most discussed mystery in the history of mysteries is this prehistoric monument that took Neolithic builders an estimated 1,500 years to erect. Located in southern England, it is comprised of roughly 100 massive upright stones placed in a circular layout, the earliest parts constructed an estimated 5,000 years ago. While many modern scholars now agree that Stonehenge was once a burial ground, they have yet to determine what other purposes it served, who is responsible for its conception, and how a civilization without modern technology—or even the wheel—produced the impressive monument. Its construction is all the more baffling given that the sandstone slabs of its outer ring hail from quarries traced all the way to the Preseli Hills in Wales, some 200 miles from where Stonehenge sits on Salisbury Plain. Some scientists have suggested that glaciers, not humans (or aliens), did most of the heavy lifting.