Top 30 Greatest Historical Mysteries

#30: Roman Concrete

One of the most impressive aspects of the ancient Roman Empire is the architecture. Several buildings from that era are still standing, serving as a testament to the skill and materials used. However, their durability left modern researchers with one question – why do those structures remain when newer ones have crumbled? For years, experts have tried to understand what made them so sound, and the answer was finally confirmed in 2023. The credit goes to volcanic ash and lime clasts, the former of which kept cracks from spreading, and the latter repairing them. With this information in mind, some modern American architects have been able to craft their own version of Roman concrete, which has helped cut costs and reduce environmental damage.

#29: The Atacama Skeleton

The quest to discover extraterrestrial life has led to plenty of historical discoveries being misinterpreted. One of the most infamous was the finding of a six-inch corpse in Chile in 2003. Its small stature, missing ribs and elongated head led to immediate claims of it being proof of an alien race. However, experts weren’t so sure. After extensive research and DNA analysis, it was estimated in 2018 that the body was that of a premature fetus exhibiting signs of various genetic disorders like scoliosis and dwarfism. While those findings have been questioned by others conducting similar research, as of 2025 no other studies have been put forward or accepted, leading many to accept the 2018 findings as the truth.

#28: The Great Wall of China

A structure this vast and ancient is bound to have plenty of mysteries. The Great Wall of China is no exception. Many assumed it was built as one large project, but had no idea how it came to be. Smaller walls and structures had been constructed by various states using natural materials as far back as 221 BC. Slowly, the different pieces were put together to form one long barrier. Each dynasty contributed to the wall’s impressive stature across a period of thousands of years, from extending it to reinforcing it with modern-day materials. Learning this has opened the world’s eyes to how one of its most iconic landmarks came to be – and it’ll be interesting to see how it’s improved going forward.

#27: The Nazca Civilization

They aren’t the first culture to have been lost, but their extinction mystified historians for years. Despite the Nazca civilizations’ advancements, they were seemingly wiped out with little explanation. For some time, it was believed they met their fate by hurricane. That only scratched the surface of the truth. While the natural disaster may have been the final blow, it was made worse by deforestation in the area. The trees were crucial in keeping the zone safe from various erosions. Without them, the people living there were left high and dry after the El Niño event – literally. Not only does this revelation answer questions about the past, it also serves as a warning for those in the present who are potentially repeating the same mistakes.

#26: Lost City of Helike

You’d think a whole metropolis vanishing as far back as 373 BC would have no chance of being found. After an earthquake caused a subsequent tsunami, the city of Helike and everyone inside it sank into the ground, never to be seen again – until 2001. Though multiple investigations had taken place in the years prior, it wasn’t until the 21st century that real strides were made. That year, the municipality was found in the depths of a lagoon, bringing the millennia-long search to a close. Multiple excavations have brought forth various artifacts, some dating back to Helike’s inception. Each discovery has allowed experts to learn more about the settlement and time period, and there’s no telling what will be uncovered next.

#25: Wow! Signal

Those disappointed in the findings of the Atacama skeleton findings may not like hearing this, either. In 1977, the Wow! signal made waves amongst the theorist community. The radio signal picked up that day certainly was strange – it seemed to come from a constellation and lasted for over a minute. Many believe it was a communication attempt from another civilization amongst the stars. In 2024, a new solution was presented providing more insight into the phenomenon. Experts have posited that the transmission was the result of a massive collapsed star colliding with hydrogen gas, resulting in a sound so loud that it was picked up by radio waves. While this is still being investigated, it's the biggest stride made so far in this decades-long mystery.

#24: The Ivory Man’s True Identity

Scientific advancements have allowed us to re-examine archaeological mysteries and uncover seemingly small secrets that rewrite history entirely. When a human skeleton was found buried in a lavish grave amongst ivory artifacts in the Spanish megalithic site Tholos de Montelirio in 2008, it was assumed to be a man. That assertion wasn’t questioned until the body’s tooth enamel was analysed, leading to a shocking discovery – that the Ivory Man was actually a woman. Then, another fancy grave containing female remains was found. This made it clear to researchers that women had more power back then than originally thought, contradicting much of what had been believed about ancient gender roles.

#23: Wiltshire Crop Circles

Sorry, but this one isn’t aliens either. There have been thousands of cases of crop circles being created, but some of the most well known have been found in or near Wiltshire, England. The occurrences date back decades, and in some cases witnesses even claimed to have seen UFOs in the area. Many assumed the designs were the work of aliens or supernatural creatures. In 1991, two jokesters, Doug Bower and Dave Chorley, admitted to creating hundreds of the crop circles, even recreating the process on camera to prove it. After they demonstrated their technique, even more circles began appearing all over the world – likely the work of copycats.

#22: Ötzi the Iceman

Finding him was only half the battle. Though the discovery of Ötzi in 1991 was in itself a historical feat, experts weren’t close to uncovering all the secrets he had to offer. Given that he was a mummified corpse, people were left to their own devices in reimagining him. Many assumed that his complexion had darkened thanks to the preservation process, so their depictions of him had fairer features. DNA testing carried out in 2023 revealed that he was likely darker-skinned, throwing people’s previous misconceptions to the wayside. It was also found that the Iceman was probably bald. The findings serve as a lesson that even the most concrete beliefs can be overturned with more evidence.

#21: Herculaneum Papyri

Mount Vesuvius exploding in 79 AD led to the destruction of much of the region of Campania and the knowledge in it. One of the biggest losses was the Herculaneum papyri, a collection of over 1,800 scrolls containing the works of prominent philosophers, which were believed to be too damaged to read. It seemed that their secrets were lost forever – until the 21st century rolled around. With it came the use of digital unrolling methods rather than physical, and soon the Vesuvius Challenge was born. It offered a cash prize for deciphering the texts, and in 2023, the first word was revealed. There’s no telling what philosophical and historical insight we’ll gain as the unraveling continues.

#20: King Tut’s Tomb

A young man named Tutankhamun ruled Ancient Egypt between 1332 and 1323 BC. You may have heard of him. By the early 20th century, experts theorized that Tutankhamun was buried in the Valley of the Kings alongside other pharaohs, but the location of his tomb remained elusive. By 1912, it was believed that every tomb had been accounted for, except for King Tut’s. So where the heck was it? Enter Howard Carter, who hit the jackpot in 1922. Unlike other royal graves, which had been cut into the Valley’s slopes, Tut’s was dug into the ground and hidden by debris. Carter’s work unveiled not only the location of King Tut’s tomb, but why no one else had been able to find it.

#19: The Connecticut Vampire

The Greater New England area suffered a vampire panic back in the 19th century, and this was exemplified through the burial of JB55. This code name was spelled out in brass tacks on the man’s coffin, and his skull and femurs were placed in the shape of a traditional skull and crossbones. Decapitating a body and arranging its bones in such a way was a historic method of burying suspected vampires. So did we have a real, genuine one on our hands? Of course not. A DNA test done in 2019 identified this “vampire” as John Barber, aged 55. Hence “JB55.” Barber had most likely died of tuberculosis, which gives people vampiric symptoms like pale skin, red eyes, and a bloody mouth.

#18: Blood Falls

Antarctica contains a startling image. Well, the whole continent is pretty darn startling, but we’re talking specifically about Blood Falls. Found in southern Antarctica in the Taylor Glacier is a small cascade of what looks like deep red blood. This was discovered by the Glacier’s namesake, Thomas Griffith Taylor, in 1911. Of course, no one genuinely believed that it was blood. Yet no one knew what it actually was. For a long time, the leading theory was that red algae was responsible for the distinct color. However, recent analysis has proven that the bold red comes from the presence of iron oxide. The iron salts inside the subglacial water oxidize when they reach the surface, changing the liquid from clear to red.

#17: Ancient Viking Code

There’s a lot to find fascinating about Vikings, including their system of writing. Like many ancient texts, the Jötunvillur, a rare Norse code, which dates back to the 12th or 13th century, left experts puzzled for years. It wasn’t until 2014 that K. Jonas Nordby of the University of Oslo figured it out. The Jötunvillur had popped up on many rune sticks, but the one from which Nordby was able to decipher it, which he calls his Rosetta stone, was located at Bergen wharf, Norway. What made these runes so hard to crack was that they were coded, likely owing to their use as an educational tool. There’s nothing juicy in the writings, but cracking an ancient code is still incredibly exciting!

#16: The Starchild Skull

It’s amazing how often conditions and diseases are misattributed to the supernatural. We’ve seen it with the Connecticut Vampire, and we see it again with the so-called Starchild. The distinct skull of the Starchild was obtained by paranormal author Lloyd Pye, who asserted that it belonged to a human-alien hybrid. This news captured our collective imaginations, but it’s really an unfortunate labeling of a tragic reality. Tests done in the late ‘90s and early 2000s proved that the skull belonged to a young human male. Sorry believers, there’s no aliens here. Furthermore, Yale neurologist Steven Novella attributed the cranial deformations to hydrocephalus, a condition in which cerebrospinal fluid accumulates in the brain and enlarges the head.

#15: The Lost Army of Cambyses

Serving as the second King of Kings of the Achaemenid Empire, Cambyses II ruled from 530 to 522 BC. Legend has it that in 524, Cambyses sent a massive army against the Oracle of Amun in the Siwa Oasis. However, the army was accosted by a devastating sandstorm and all 50,000 men were lost. For a long time, the veracity of this tale was questioned, as its primary source was the Greek historian Herodotus, who has been known to, shall we say, dramatize certain events. But in 2009, archaeologists Angelo and Alfredo Castiglioni found human remains and Persian belongings near the Siwa Oasis, finally lending credence to the story. However, it’s important to note that some experts doubt the findings of the Castiglionis.

#14: The Flying Dutchman

You’ve probably heard of The Flying Dutchman, as it’s been featured extensively in art, television, and film, including the “Pirates of the Caribbean” franchise. This is an alleged ghost ship that inspired many a tall tale, with the legend dating back to the 18th century. It is said that the Flying Dutchman floats above the water and contains a crew of cursed and undead sailors. Reports of the ship even stretched into the 20th century, and that’s because optical illusions are timeless. Yep, the Flying Dutchman is not one ship, but the result of an optical illusion called Fata Morgana. Essentially, some ships on the distant horizon look like they’re floating owing to how light travels through different layers of air.

#13: The City of Troy

And speaking of legends, it doesn’t get much bigger than the Trojan War. A favorite subject of Ancient Greek literature, the Trojan War details the invasion of Troy by the Achaeans. Many scholars debate the history of the war itself, and for a long time, they debated the location of Troy as well. Most thought it was merely a place of legend, but that viewpoint changed thanks to Heinrich Schliemann and Frank Calvert. In 1871, the archeologists began excavations in present-day Hisarlik, Turkey and discovered not one city, but nine. Each city was built on the ruins of the last, resulting in numerous distinct layers labeled by Roman numerals. It is now widely believed that Troy VI is the one depicted in the Greek myth.

#12: The Easter Island Heads

The Moai, as they are properly known, are some of the most recognizable monuments in the world. Populating Easter Island in Polynesia, the Moai were carved in a volcanic crater called Rano Raraku. They were then transported to the outer perimeter of the island, where they rested on platforms called ahu. We don’t really know how the natives moved the statues, and for a long time, we didn’t know why they chose the sites that they did. Well, that particular question was solved in 2019 by researchers at Binghamton University. They discovered that the ahu were placed near sources of fresh drinking water, because that’s where communities were inclined to settle. It’s not dramatic, but it sure is practical!

#11: The Classic Maya Collapse

In the span of human history, the Maya collapse wasn’t all that long ago, with the last city falling to Spanish settlers in 1697. But another major collapse occurred earlier, with most of the major Maya cities being abandoned between the 7th and 9th centuries. The reason for this is one of history’s greatest unanswered questions. Well, it was. Until 2012. Turns out, a number of factors went into the collapse, as it so often does. The Maya greatly deforested the surrounding area, which exacerbated an ongoing drought and killed all agriculture in the region. Furthermore, trade routes had changed from land to sea, impacting local economies and forcing a relocation from the Southern Lowlands to the Northern Yucatán.

#10: The Fate of the Franklin Expedition

Captain Sir John Franklin’s Arctic exploration expedition was lost after leaving England in 1845. Over the years, many other ships set out to see if they could find out what happened to the doomed crew. While some clues were found, including gravesites of some of the men who had been aboard, it was only at the end of the 20th century that we began to get answers about what had caused Franklin and his team so much trouble. Unfortunately, we discovered that many of the crew members did not die quickly but rather succumbed to diseases like scurvy and even lead poisoning after becoming icebound. And sadly, the rumors of cannibalism were also proved to be true...

#9: Mysterious Notes in “The Odyssey”

Homer’s epic Greek poem “The Odyssey” has become known as one of the most important pieces in the history of literature. While there are many things that we still don’t know about the story’s creation, an extra layer of mystery was added when a copy was found with unintelligible notes in the margins. The copy belonged to the University of Chicago Library and was a Venetian edition from 1504. The library created a contest to see if anyone could crack the code, and Italian computer engineer Daniele Metilli figured it out with help from colleague Giula Accetta. It turns out the notes were written in a French shorthand and dated from the 19th century.

#8: King Richard III’s Death

While his legacy has lived on through Shakespeare, King Richard III of England was the final English king to perish in battle. In fact, his death during the Battle of Bosworth Field is often used to mark the end of the Middle Ages. But his remains were lost, and only uncovered in 2012 during an archaeological excavation in Leicester. The following year, the body was identified as belonging to Richard III. He had suffered 11 wounds, most of which were on his skull, which suggests that he lost his helmet in battle, leading to his demise.

#7: The Sailing Stones

Known as sailing stones or moving rocks, observers have long noticed the enigmatic phenomenon of these objects that seemingly move on their own, leaving trails in their wake. The most famous example is found in Racetrack Playa in California’s Death Valley National Park. Many experiments have been undertaken in an attempt to understand how these large objects move, and we now seem to have an answer. On cold nights, thin sheets of ice develop under them and then float and are able to be moved by the wind, which propels the rocks as fast as five meters per minute.

#6: The Face on Mars

Between the Arandas Crater and Bamberg Crater in the Cydonia region of Mars, spacecraft Viking 1 captured an image in 1976 that has fueled speculation for decades. That’s because it looked, for all intents and purposes, like there was a face on the Red Planet. While people wanted to use this as evidence of an alien civilization, the actual explanation is a banal one. Scientists have agreed that the face is essentially an optical illusion, and that it’s only present based on the angle from which you view it and how well-lit it is.

#5: The Location of the USS Indianapolis

The sinking of the USS Indianapolis is amongst the greatest tragedies that the American Navy has ever experienced. Torpedoed by a Japanese submarine in 1945 during a mission to deliver parts of the nuclear weapon Little Boy, there were only 316 survivors from a crew of 1,195. The wreck remained unfound, despite several expeditions to locate it. But in 2016, new information was revealed that gave us a better clue of where it might be, and in 2017 a team funded by Microsoft co-founder Paul Allen finally found the well-preserved remains of the ship.

#4: How the Pyramids Were Built

The Egyptian pyramids are one of Earth’s most widely recognizable landmarks. But for many years, people wondered how they were possibly built without modern technology. Was it aliens? Well, probably not. It had already been known that the Egyptians likely used wooden sleds to drag large objects across the sand, but researchers at the University of Amsterdam added a probable solution to make this even easier. They established that by wetting sand, only slightly, it would create the perfect amount of friction to carry very heavy objects easily. Another ancient Egyptian mystery that has a more clear-cut answer is the hieroglyphs that seemingly depict modern helicopters. It turns out that these are a product of the stone being reused for more than one image.

#3: What Caused the Tunguska Event

In a remote area of Russia in 1908, a massive explosion took place that flattened tens of millions of trees and produced an estimated 185 times more energy than the atomic bomb dropped on Hiroshima. It inevitably left many wondering what had caused it. For decades, people have speculated that it might have been an asteroid, a comet, a clash of matter and antimatter, or even an alien spaceship landing. But in 2013, it was essentially confirmed that it was in fact a meteor when a team from the National Academy of Sciences of Ukraine analyzed rock samples of meteoric origin from the site.

#2: The Bermuda Triangle

While some of the other mysteries on our list may not be commonly known to the general public, nearly everyone has heard of the Bermuda Triangle. For many years, people have wondered about the evils at work here that seemingly make boats sink and planes fall from the sky. But the explanation is simple and unexciting. While some may imagine the Triangle as a small and specific area, it’s actually a huge (and not well defined) region that is heavily trafficked by sea and by air. In fact, your cruise ship may have sailed right through it without you noticing. Yes, plenty of accidents have occurred there, but they largely have logical explanations.

#1: Anastasia’s Escape

In 1918, the Russian Imperial Romanov family was executed by communist revolutionaries, but for years rumors persisted that Tsar Nicholas II’s youngest daughter, Anastasia, somehow survived and escaped. It didn’t help that several women throughout history have impersonated the supposedly missing princess. These speculations were fueled when the Romanovs’ grave was found in 1991 and two bodies were seemingly missing. But by 2007, another gravesite had been found nearby, and DNA evidence conclusively proved that all members of the family are accounted for. It’s a sad ending to the tale for those who preferred to hold out hope of her survival.

What historical mystery do you find the most fascinating? Let us know in the comments below!