1. The mystery of Stonehenge

Stonehenge has been baffling experts for centuries, and pretty much every year, one of them comes out with a new theory on how it was built and what its purpose was. Trying to find the answers to these questions have left researchers twisted up like a rolled cigarette. It’s been around so long, it’s like a joke that’s so old nobody remembers where it came from.

2. What was it built for?

The first problem with Stonehenge is that 43 surviving bluestones (which weigh 8,000 pounds each) were transported over 200 miles to the site. Theories abound from glaciers depositing bluestones on the landscape, to the use of ancient barges over water, giant wicker baskets (really), or perhaps even rolled over logs.

The purpose of Stonehenge might be even more baffling. It was probably used as a burial site for at least some time, and could’ve also been some sort of cosmic map or astronomical calendar. What makes it hardest is that there’s evidence many different tribes contributed to its construction and used it for rituals. We just don’t know for certain what those were.

Next: Some freaky stuff.

3. Why did Greek Fire disappear?

Most of our list includes structures and archaeological finds, but in this case, it’s a recipe. The weapon known as Greek Fire won the Mediterranean Sea for the Byzantines in a time when the use of explosives in warfare was still a good 400 years off.

The recipe for this early form of napalm was lost to history, and for centuries, scientists and military historians were flabbergasted by this fabled weapon. Warfare on the high seas was fought by ramming enemy ships, and Greek Fire is said to “cling to flesh and was impossible to extinguish with water.” That’s a very powerful weapon for the sixth century, but what is it actually made of?

4. A secret lost

The recipe for Greek Fire is said to have belonged to a Greek family that lived within the Byzantine Empire. Tubes, likely made of bronze, were mounted on the prows of ships, and the fire was spewed onto enemy ships. Throwing water on it was said to make the fire spread even more. So much for fighting fire with fire.

We can thank National Geographic for producing the most plausible theory for what Greek Fire really was. Back in 2002, they used a bronze pump to fire a mixture of oil and pine resin that burned a wood ship in a matter of minutes. Had Greek Fire not been lost to history, it would’ve been around when empires were warring in seas all over the world. Whew!

Next: Mysterious heads in the far flung regions of the Pacific

5. Easter Island heads of Rapa Nui

Sometime around the year 800, a small tribe of 100 brave souls is said to have traveled thousands of miles to settle on the shores of Easter Island. For the next 1,000 years, they conducted a ritual of carving and planting some 1,000 Heads of Rapa Nui (Easter Island).

We still don’t know why the inhabitants of Rapa Nui transported the large rocks, carved their features, and placed them in the ground facing away from the sea. We think we know how they were moved, but before European explorers arrived on Easter Day 1722, the secrets were lost to history.

6. Down deep

The disproportionate heads are almost comical, as some of them protrude 13 or 14 feet out of the ground. Unbeknownst to the untrained observer, the statues can measure up to 40 feet high, because the torsos propping up those giant heads are buried deep into the ground.

By the time explorers showed up, the heads were in such a state of neglect that they were falling off. The most widely accepted theory is that they are a form of tombstones, as families of bodies are buried next to the heads. They were also originally painted red, which may have been part of a funeral type ritual.

Next: Skillful carvings of God knows what…

7. Perfection in Puma Punku

When a civilization is conquered, then another group comes in and conquers them, the original civilization has a hard time surviving history. Case in point are the extraordinarily mysterious ruins (if we can even call them that) of Puma Punku. The reason we have a hard time calling Puma Punku ruins is that the precision at which the rock carvings accomplished is absolutely astounding.

With laser-like precision, the shapes etched into stones don’t even bear the traces of a chisel. They were so impressive that after the Incas took control of the ancient city in 1470, they came to believe the carvings represented the first humans, and were at the heart of their beliefs around creationism.

8. Needle-like precision

It’s more likely that the statues are former leaders of the city Tiwanaku, in which Puma Punku is located. Archaeologists have determined that the ruins are a mind-blowing 17,000 years old. To put that in perspective, consider that the Great Pyramid of Giza was built 12,000 years after Puma Punku.

The precision of the carvings is needle-like, and it’s too bad the original inhabitants aren’t around still around because mastering those techniques so early would’ve yielded more fantastic pieces. Today it exists in modern-day Bolivia, which may be why it doesn’t get as much attention as Stonehenge. None the less, that level of precision was unmatched in the ancient world.

Next: Anachronistic swords

9. Ulfberht Viking Swords

Valyrian steel… er, excuse me, Ulfberht Viking swords are an anomaly fit for fiction more than history. These powerful blades were so exceptional because they were way before their time. In fact, modern historians still don’t know how a blade of that quality could be made hundreds of years before the method to produce them was invented.

Ulfberht swords were dated to be over 1,000 years old, and the method for producing steel of that quality didn’t exist until 800 years later. Accounts of soldiers facing the strong swords say that the Vikings had a mysteriously strong weapon that could bend and slash through any metal armor.

10. 800 years ahead of its time

The Industrial Revolution created the methods necessary to produce a sword of that strength and flexibility, but in the year 800, the technology was still centuries off. The carbon content of a sword is extremely important to make it strong, and Ulfberht swords are said to have three times the carbon content than other swords of the era contained.

To create a sword so absent of impurities, the blacksmith had to reach a temperature of 3,000 degrees Fahrenheit. Such methods were not around, but some historians have surmised that the method may have come out of the Middle East, where sword making methods baffled European invaders during the crusades.

Next: Damascus steel

11. Damascus steel

In the 9th century, a Viking man was buried in Scandinavia. When archaeologists unearthed his grave, they were baffled to read an inscription that read, “for/to Allah.” The link between Islam and Vikings is not one that has been well researched, but clearly, there’s something going on.

To explore this link a little further let’s take a look at the sturdy, yet lightweight and strong Damascus steel. Crusaders coming back to mainland Europe complained of the enemy wielding a sword, “that could slice through a floating handkerchief, bend 90 degrees and flex-back with no damage.” Knowing that Vikings traveled a lot, it is possible that they had some trade relationships established with the Middle East and learned how to produce the coveted steel.

12. Huge advantage

Imagine the horror the lowly fighter faced when he watched his comrade flash his sword to block a swing from an enemy sword, only to watch the enemy sword slice through the inferior blade. That’s Damascus steel. It gave Islamic fighters a huge advantage over their Christian foes.

It seems likely that the makers of Damascus steel used what’s known as “crucible steel,” then upped the temperature when melting the steel by using melted iron and plant matter. But to this day historians and archaeologists are having a hell of a time trying to duplicate the recipe, meaning it might be lost to history.

Next: Giant insects.

13. A message to the sky

In the arid lowlands of modern-day Peru, there exists a series of carvings of plants, insects, and animals, visible from the sky and meticulous in their shape. It’s no mystery what the carvings that can span two football fields depict, or even how they were created. But just what exactly it was made for is a mystery.

The Nazca tribe painstakingly scraped away the copper surface of rocks on the floor of the desert, which exposed the lighter earth below. The area that the Nazca used for their fields of carvings is extremely arid, and the lack of rain has left them largely intact.

14. Where have the Nazcas gone?

It seems that, like natives of Puma Punku, when you spend a lot of time on art instead of warfare your civilization gets conquered and assimilated into a bigger one. That’s not an absolute, but the Nazcas endured a terrible drought in the 5th century and then were conquered by the Wari, who took on many of the Nazca’s artistic prowess.

Many civilizations of ancient times believed that their gods were in the sky, and nowadays when we think of heaven, where do we look? The Nazca had beliefs similar to that of the Egyptians and the Mayans, that the gods in the sky could see them on the ground. It’s likely that’s why they made them, but no one really knows for sure.

Next: Ancient airplanes.

15. The Quimbaya Airplanes

The Nazca lines are best viewed from the air, and even though flight didn’t come around until 1903, somebody forgot to tell the people Quimbaya. The Nazca in Peru had neighbors to the east in modern day Columbia, and just like them, they came up with some mind-boggling pieces of art.

The Quimbaya Airplanes were created over 2,000 years ago, and are so outrageously ahead of their time some believe aliens or even time travelers inspired their creation. The reason why these theories can’t be discarded is because the aerodynamics of the airplanes have been tested, and the airframe would work for both propellers driven and jet aircraft!

16. Testing the airframe

In 1994 a pair of German aeronautical engineers created scale models of the Quimbaya Airplanes and tested their aerodynamic properties and proved that they could fly. They don’t resemble any insect or creature ever found alive or in fossil form, so where the heck did they come from?

Archaeologists can’t say for sure what they were used for and might even say the fact that they were shaped to fly might be a coincidence. The Quimbaya were largely destroyed by the arrival of Conquistadors in the 1500s, so we may never know why or for what purpose they were created.

Next: The ultimate head-scratcher.

17. The Piri Reis Map

This next one comes from a discovery that was made early in the 20th century, and has historians completely bamboozled for multiple reasons. It seems that the chicken came before the egg in the case of the Piri Reis Map, because it contains accurate drawings of land that hadn’t been discovered yet.

Not only does it contain drawings of land that hadn’t been discovered, but it also has drawings of land that’s never been seen. The land is Antarctica, and the map precedes its discovery by 300 years. Moreover, it depicts Antarctica perfectly as it was 6,000 years ago. Let’s explain that a little further.

18. Christopher Columbus contributed to the map

The map was discovered amongst a pile of discarded items in 1929. The author of the map was a Turkish admiral and cartographer named Piri Reis. We know a little bit about him and his effort to create this map. He said he used 20 different maps to create this one, including one from Christopher Columbus.

But the fact remains that the least astounding thing about it is that it shows Antarctica 300 years before it was supposedly discovered. The most incomprehensible part is that it depicts the coastline of Antarctica as it was 6,000 years ago, before it was covered in ice. Time travel and aliens are starting to make more sense because Piri Reis Map is inexplicable.

Next: An untranslatable language.

19. 500 years without answers

It’s a book without an author, a discernible language, or even a vague idea of what it’s trying to say, but the Voynich Manuscript has been confusing linguists for 500 years. It’s like an elaborate ruse on language (and there are theories that it’s just a giant prank) and perhaps only now are we getting a handle on translating it.

Earlier in 2018, an Electrical Engineer and linguist enthusiast named Ahmet Ardic brought his theory forward. He found the manuscript online in a Reddit post and spent the next four years deciphering its hidden meaning. What he found is compelling and under scrutiny from scholars and linguists alike.

20. Ancient Turkish?

The Voynich Manuscript gets its name from the Polish man who reportedly bought it from Jesuit Monks in 1912. Prior to that, it had been passed around since at least the 16th century, and no one has solved its riddle, until now.

Ardic believes that the writing is Turkish and claims to have translated over 300 words in the manuscript. He also made a compelling case for the translation of a calendar and is continuing with his work to this day. Skeptics doubt the amateur linguist, but Ardic may have finally cracked the code of the Voynich Manuscript.

Next: An ancient Sumerian mystery

21. Blending truth and fiction

The line between fact and fiction is something we struggle with even in present times, and the Sumerian King List seems to blur that line like a hazy fog. The list is a historical record to a point, as it names the kings and the periods in which they reigned, but it also includes mythical kings that ruled for time periods that are impossible.

The first cuneiform tablet was discovered in the ancient city of Nippur in the early 1900s, and translated shortly after. Since then, 18 more tablets have been discovered that testify to the listing of kings, and historians were perplexed by what each one had to say.

22. What’s real, and what’s not?

Archaeologists have been able to carbon date the tablets back to sometime around 4,000 BC, and each tablet says something different about the reigns of various kings. But researchers have found common threads that match up to other historical data.

Sumerian kings were believed to be ordained by the gods, but not actually to be gods themselves. So it seems confusing that the historical record would indicate reigns lasting up to 1,000 years. We know what you’re thinking — aliens strike again, but really, an elaborate ruse seems more fitting, as researchers have known about it for over 100 years and are still trying to figure it out.

Next: The answer to the Sumerian King List Riddle: Lizardmen.

23. Yonaguni Monument

This one was only recently discovered and will likely be under debate for a long time. As long as no overriding evidence comes forward, the origins of the Yonaguni Monument may always be unknown. So is it real, or was it built by people?

The problem of the Yonaguni Monument is that its too perfect to be natural, and yet there is no evidence or artifact that says human beings created it. Not only that, but it’s far enough underwater that it’s only accessible by scuba diving. Scuba diving was how it was discovered in 1987 when a divemaster was looking for hammerhead sharks.

24. Where did it come from?

Now most divers skip the sharks and head for the Yonaguni Monument. Some of its features resemble man-made objects such as pillars, a star, and geometric shapes. While the stone was likely deposited their 20,000,000 years ago from a glacier.

Those who believe the rocks were carved by people think it was done over 5,000 years ago, and varying theories exist as to how the Yonaguni monument ended up underwater. What seems to be most likely is a geometrically natural formation was modified by humans, but the part about being underwater presents problems for humans being involved in the first place.

Next: Giant balls

25. Giant Balls of Costa Rica

When it comes to ancient cultures of Mesoamerica it seems that many had a penchant for creating large scale carvings to perfection. In the case of the Giant Stone Balls in Costa Rica they certainly fit the bill and were created around a similar time that the Nazca and Quimbaya were doing the things they did to provide jobs for future generations of historians.

There’s a problem with the Giant Balls in Costa Rica however, as unwitting vandals and others have moved them from their original location. While several theories exist as to what they are, it may never be known for this reason. At least a few of the balls had their revenge on the vandals.

26. Perfect balls

The Giant Balls were created using various techniques of “fracture, pecking, and grinding” to the stone. Theorists contend that the balls may have been an ancient calendar or even a navigational tool. But again no one can say for sure because of the pesky vandals.

According to local legend, vandals got word that there was gold inside, then went so far as to blow up balls to see if there was any inside. Some gulliballs (pun intended) never learn, and neither will historians ever learn the true origin of the Giant Balls of Costa Rica.

Next: A mystery from the bottom of the sea.

27. 2,000 years ahead of its time

Just like the Giant Balls of Costa Rica (sorry we’ll stop bringing them up now), the Antikythera Mechanism was likely built around 200 BC. It was pulled from the bottom of the ocean in 1901, and that’s when researchers went to work trying to decipher its origin.

It’s a gear-based mechanism that’s meant to help ancient mariners navigate, and includes both a lunar and a solar calendar, as well as information regarding the stars. But it wasn’t so much that historians didn’t know what it was for, but the fact that it was a full millennium before that kind of technology was around.

28. Inexplicable

Time travel enthusiasts, or conspiracy theorists if you want to call them that nearly shut down the internet in 2006 when it was theorized that the 2,000-year-old mechanism was from the future. The theory that prevails, however, is far less cool, but at the same not so plausible.

One historian theorized that anything such as the Antikythera Mechanism that’s made of bronze would’ve been recycled over the years and turned into something else. Well, historical data doesn’t necessarily back up that prevailing theory, and generations since have wondered how that kind of mechanism would escape any kind of record. Like most finds on this list, it just may be inexplicable.

29. Roman Dodecahedron

This one’s a little weird. Most of these finds remain mysterious because the people who created them were wiped out for one reason or another. But the Dodecahedron was something that was made by Romans, whose mark on the planet and the history of mankind was hardly erased from the books.

And yet here we are with the Dodecahedron, an object that is literally littered throughout the vast Roman Empire that spanned an entire continent, and yet we have found absolutely no historical reference to it. Just like the Voynich Manuscript, about every year someone comes out and says they “solved” the mystery.

30. Are we being mocked?

There have been there fair share of guesses that basically equate the Dodecahedron to an inanimate object meant for décor, such as candle and flower stands. They may also be ancient dice or hold some religious or cultural significance, but no one really knows for sure. They’ve even been said to help farmers determine when planting season begins.

This might mean that we’re ogling over something completely insignificant, which could also mean that some time traveler from the future placed this object in the past just to mess with us. We hate to admit it, but it appears their pranks are working.

This story was originally published on History 101.com