“Even the most painstaking history is a bridge across an eternal mystery” —Bruce Catton

Some of our greatest mysteries may never be solved, while others harbor their solutions just under the surface, waiting patiently for someone to unearth them. Let’s look at some of the biggest and most baffling historical mysteries of all time and share what we do know.

20. Riddle Me This

By far the largest statue that has survived from the ancient world, the Great Sphinx of Giza has been perplexing archaeologists for many years. The sphinx was only re-discovered in 1905; before that, it was covered in sand, and we have no way of knowing what its creators called the statue.

19. Dance the Night Away

In July 1518, a woman named Frau Troffea turned onto a narrow street in Strasbourg and was suddenly compelled to start dancing. This convulsive, involuntary dancing fever gripped her for days, and then began to grip others. About 400 people were infected with the so-called "dancing plague" over the next month. This was all totally groovy until people started to collapse from exhaustion or die from heart attacks and strokes. This went on until September, when the dancers were taken to a mountaintop shrine to pray for absolution.

18. From Hell

In London, 1888, at least five women were killed and dismembered in what became known as the Whitechapel murders. The identity of the killer, known only as Jack the Ripper, has been the subject of fevered puzzlement and speculation ever since, inspiring countless theories and works of fiction. The name came from a series of letters (signed “Jack the Ripper”) sent to the police, taunting them over their efforts to find the killer. The five murdered women who definitively share characteristic marks from the Ripper are called the "Canonical Five."

17. Flying Solo

During an attempt to circumnavigate the globe in July, 1937, American aviator Amelia Earhart disappeared somewhere over the Pacific Ocean. The wreckage was never found, and her disappearance remains one of the most iconic unsolved mysteries of the 20th century. Before her disappearance, Earhart was the first woman to fly solo above 14,000 feet and the first woman to fly solo across the Atlantic ocean.

16. Unbreakable

Written sometime in the 15th or 16th Century in central Europe, this mysterious folio is painstakingly illustrated with strange plants, astrological charts, and naked ladies bathing in some kind of green liquid. Its script is written in an indecipherable language that has eluded historians and cryptographers to this day. One recent purported solution claims the manuscript was a women's health manual, but this claim has been criticized.

Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19

15. The Mary Celeste

On November 7, 1872 Captain Benjamin Briggs, his wife, young daughter, and a crew of eight departed New York on the Mary Celeste brigantine. They were never seen again: On December 1872, the ship was discovered floating in the middle of the ocean with not a soul on board. Aside from a missing lifeboat (and chronometer and sextant), the ship had sustained no damage, and was stocked with food and supplies. There was no indication of why the crew would jump ship, never to be heard of again.

14. The Princes in the Tower

In the summer of 1483, two young boys, Edward V of England and Richard of Shrewsbury, were locked in the Tower of London and never seen again. Thought to have been murdered, they were the sons of Edward IV and his Queen, Elizabeth Woodville, and the prime suspect has always been their uncle, Richard III, although evidence has always been circumstantial. In 1647, Tower workmen unearthed a box containing two small skeletons that were presumed to belong to the princes. However, new evidence suggests that these skeletons were not related to Richard, creating one more mystery.

13. Crystal Clear

This real-life archaeological enigma isn’t just the kooky brainchild of latter day Spielberg and Lucas. Long rumored to have originated in Maya and Inca civilizations, there are some who claim that these carved objects have healing qualities or are caches of ancient wisdom. Scientific research has concluded, however, that they were most likely produced in Europe in the 19th century, but by whom and for what purpose remains a mystery.

12. Stonehenge

Built between 4,000 and 5,000 years ago, Stonehenge is one of the most enigmatic ancient monuments in the world. Presumably built and used for ceremonial purposes, the exact function of the monument remains a mystery, as does the question of how those huge stones were transported 260 kms across prehistoric Britain. However, new research shows Stonehenge was likely a part of a complex of ritualistic structures including ancient burial mounds and processional routes.

11. Linemen

Located south of Lima, Peru, the stunning geoglyphs of Nasca cover an astounding span of land and can only really be appreciated from the air. The geoglyphs depict distinct animal shapes and other enigmatic figures, and we still don’t know how and why they were created.

Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19

10. Men in Tights

He’s the archetypal outlaw with a heart of gold, but we have no idea if a real Robin Hood ever existed at all. Several men could have been the inspiration for the legend, and the historical evidence puts him all over the map. Maybe even the hardest to trace? "Robert" was a common name at the time, and both makers and wearers of hoods were often called "Hood." Personally, I’ll continue to think of him as a talking fox.

9. The Black Dhalia

On January 15, 1947 the body of Elizabeth Short was found in a vacant lot in Los Angeles. She’d been cut in half, drained of blood, and three gashes had been cut into the corners of her mouth, imitating an eerie smile in the style of a "Glasgow smile." The gruesome murder quickly became a sensation, but in spite of one of the largest police investigations in history no charges were ever filed. Most mysterious? Despite the fact that the killer drained Short of blood, there was no blood on the scene.

8. A Different Kind of Adventurer

The Irish Crown Jewels were stolen from Dublin Castle in 1907, and would be worth about $20 million today—if we could ever find them. The mystery remains unsolved, although a relative of the renowned explorer Ernest Shackleton was a chief suspect.

7. The Bronze Age Collapse

Between 1200 and 1150 BCE, every major culture in the Eastern Mediterranean basin collapsed into ruin, marking the start of what has been called the Greek Dark Ages. Thing is, we have no idea what happened. Many theories have been put forward to determine the cause of the collapse, from volcanic activity to climate change to advanced weaponry. All we know for sure is that this wasn’t a great time to be alive.

6. Booby-Trapped

In 1799, a man name McGinnis discovered a sinkhole in the ground in Oak Island off of Nova Scotia. Believing there could be buried treasure, he began digging and discovered layer of flagstones. This kicked off a two century-long tradition of treasure seeking in the area, and just enough evidence has been found to keep people digging. Among the discoveries were a set of stone inscriptions, which allegedly translated as “forty feet below lie two million pounds.” No treasure has been found despite all this, but the hunt continues to this day.

Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19

5. D.B. Cooper

On November 24, 1971, a man the media dubbed “D.B. Cooper” hijacked a Boeing 747 plane, released his hostages in exchange for $200,000, then jumped out of the plane with a parachute and the loot, never to be heard from again. The FBI is no longer actively investigating the case but it has nonetheless cemented itself in American legend.

4. The Devil’s Footprints

Early on the morning of 9 February 1855, residents of Devon country, England awoke to find a single line of cloven hoof-like marks in the deep snow, almost as if they’d been burned there. The marks were found over a distance of 100 miles. People speculated that it could have been any number of different animals, or rain, or a weather balloon dragging an implement, but the more superstitious among them preferred to believe that the footsteps were left there by the devil himself. There were even reports that the hooves stopped right on the threshold of people's houses.

3. Mothman

Between November 12, 1966 and December 15, 1967, numerous sightings of a huge bird-like creature with glowing red eyes were reported near Point Pleasant, West Virginia. The creature was dubbed the “Mothman” and some residents claim to be haunted by it ever since. Skeptics have dismissed the Mothman as a hoax or a mass illusion, while others have claimed that the creature was linked in some mysterious way with the collapse of the Silver Bridge in Point Pleasant in December 1967 that killed 46 people, including some mothman witnesses.

2. The Zodiac Killer

Famous for goading the police with cryptic letters supposedly containing information leading to his identity, the Zodiac Killer murdered at least five people in North California in the 1960s and early 1970s. Arthur Leigh Allen was a prime suspect, but the evidence didn’t stack up; to this day the killer’s identity remains a mystery. During the killer's spree, police actually unknowingly crossed paths with the murderer but failed to recognize or detain him.

1. "Croatoan"

Led by governor John White, more than 100 settlers arrived at Roanoke Island, North Carolina in 1587 to establish the first permanent English colony in the New World. White departed for England for more supplies later that year, and when he finally did come back in 1590, nobody was home. The entire colony had vanished without a trace, leaving only a message that read "CROATOAN" etched into a post and the letters “C-R-O” carved into a tree. Archaeologists have suggested that the colony was assimilated into the native tribes; "Croatoan" was the name of both an island and a tribe in the area.

Sources:  1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19