According to scientists, these giant stone balls in Costa Rica were formed around ca. 200 BC to AD 800. Natives used “fracture, pecking, and grinding” techniques to reduce a large igneous stone called granodiorite into these spheres.

But no one knows why they bothered doing it.

Unfortunately, vandals have moved the spheres from their original locations. Testing theories as to their use as calendars or navigational tools have become impossible. And no, they did not contain gold.

Scholars still have no idea as to what purpose these served. The Romans could have used them as paperweights or household objects meant for decoration. Or at least that’s the idea.

George Hart of Stony Brook University notes dozens of these twelve-sided, 4-to-11 cm. spheroids were discovered throughout Europe. But somehow,the Romans never mentioned them. Could have been candle stands, flower stands, surveying instruments, finger ring-size gauges, and even gaming dice. It’s really anyone’s guess now.

The Phaistos Disc was originally found in 1908 in Crete. The 6-inch diameter clay disk dates back to 1700 BC featuring 241 “words” created out of 45 individual symbols. It’s been a mystery since its discovery.

Early theories suggested that it was “sheet music”, almost like a hymn or prayer dedicated to female deity. Some theorized that it was an ancient proto-typewriter.

Dr. Gareth Owens together with phoneticist Professor John Coleman, theorized that it was written in a Minoan script. The language was linked to a prayer to the Minoan goddesses and deities of the era.

The “Iron Pillar of Delhi” is resistant to rust. It is over 1600 years old so scientists and experts think that the mild climate of Delhi, India, is the reason for the rust-free pillar. But there are experts who studied the pillar and they say it’s the “presence of phosphorus, and absence of sulfur [and] manganese in the iron,” plus the “large mass of the pillar.”

Whatever the reasons are, it’s mind boggling.

The Vikings could have taken inspiration from the creators of Damascus steel to make their legendary “Ulfberht” swords. The blades shocked archaeologists since “the technology needed to produce such pure metal would not be invented for another 800 years.”

A 9th-century Viking grave was discovered in Scandinavia back in 2014 bearing an Islamic inscription meaning “for/to Allah,” which made the theory possible. But the blade’s origins are still unknown.

Then in 2020, German scientists discovered evidence suggesting that the Ulfberht swords were possibly created in Germany.

It’s gold, dragon-festooned, and toad-surrounded. It seems to have been the first earthquake detector dating from around 132 AD.

Basically, one of the dragons, which represented directions of the compass, would spit out a bronze ball into a toad’s mouth. That would indicate the direction of the earthquake.

It is said to have “detected a four-hundred-mile distant earthquake which was not felt at the location of the seismoscope.”

And yet no one knows what was inside the artifact. Some suggest a simple pendulum-based system, but as to the exact “science” of the artifact, that remains a mystery.

The Antikythera Mechanism was discovered at the bottom of the sea in 1901. It was likely made around the end of the second century BC. According to scientists it “calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar”.

But know one knows who built and used it, or what it’s used for, exactly. Not to mention that it is “technically more complex than any known device for at least a millennium afterwards” to quote the Nature abstract.

Many “ancient aliens” and “TIME TRAVEL IS REAL!!” blog posts came out after publishing in 2006.

Brian Dunning of Skeptoid says similar gear-based technology already existed two and a half millennia before this mechanism was found.

This is the hand-written and hand-drawn Voynich Manuscript, which researchers say features text in an indecipherable language with hundreds of illustrations that include “a myriad of drawings of miniature female forms, most with swelled abdomens, immersed or wading in fluids and oddly interacting with interconnecting tubes and capsules”.

The manuscript is said to have been created around the 15th century in Central Europe. It was a Polish-American antiquarian bookseller named Wilfrid M. Voynich who acquired it in 1912.

But that’s all the info they have on it.

An electrical engineer and his sons studied the artifact and theorized that it uses a phonetic transcription of a Turkish dialect. That led to a British researcher publishing a paper claiming the dialect was an ancient “proto-Romance” language. Both theories remain unproven.

Europeans returning from the Crusades would talk about swords wielded by Islamic warriors “that could slice through a floating handkerchief, bend 90 degrees and flex back with no damage.”

They were perplexed then and they still are today since the recipe for “Damascus steel” remains a mystery.

The best guess people have come up with is that the blades consisted of “crucible steel”, created by melting iron with plant matter. But as to its specifics, that remains unknown.

Scientists and historians are very curious about 7th-century “Greek Fire“. It’s basically a proto-napalm fired from ships that “would cling to flesh and was impossible to extinguish with water.”

The Byzantine Empire used it to great success, but the recipe for Greek Fire was a protected family secret which was never discovered.

In 2002, National Geographic had a go at guessing the ingredients, using a “bronze pump” and a “mixture of light crude oil and pine resin.”

Their recipe wiped out a ship “in minutes.”

Gobekli Tepe in Turkey was discovered in 2008. Known as the oldest-known temple in the world, it dates back 13,000 years to 11,000 BCE. This mysterious temple was built before metal tools, or pottery, had been invented but the engineering boggles researchers.

The strange animal heads that top the pillars line the temple but no one knows what they mean or what function the temple served. All they can agree on is that it serves a religious purpose.

In the 1950s, the British Museum acquired a 1600-year-old Roman chalice. It was known as the Lycurgus Cup, and it appeared to change colors depending on the light. The cup was jade green from behind but lit from in front, it became a deep, blood red. Researchers at the British Museum were baffled.

In the 1990s, researchers studied broken fragments from the cup. They found their answer lay in an ancient use of nanotechnology. The Roman craftsmen ground down gold particles until they were only 50 nanometers across. The precision of the Romans indicated that they were masters of nanotechnology.

A book written in India in 400 BCE talks about flying machines known as vimanas. The author, Maharshi Bhardwaj, described in detail how to steer them, and what pilots did to prepare for long flights. There was even a feature on how to switch the vimanas to solar energy.

The drawings and descriptions stumped researchers. The usual “aliens” theory were proposed, while others believe they’re a hoax. What we do know is that they remain to this day, a mystery.

The massive moai statues covering the surface of Easter Island enshrouds the Polynesian people in mystery. But they also had a script known as Rongo Rongo. It’s a system that used symbols, like a form of proto-writing.

But interpreting Rongo Rongo remains elusive since it is nothing like the writing styles of other neighboring cultures. The symbols seem to be religious but no has deciphered it yet.

The outskirts of Cuzco have tourists visiting the ancient Incan city in Peru where there is a fortress made of boulders that weigh over 200 tons. The boulders are fitted so perfectly together that fitting a piece of paper in between them is impossible.

Researchers don’t know how these ancient engineers achieved this level of precision. Theories suggest the use of heat or a liquid made from plants which made the boulders easier to work with. Others say that the complex we see was originally a complex made of wood. Who knows.

Watch this fascinating video for even more ancient inventions that are still baffling our scientists of today.