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Baghdad Battery (Iraq) -

In the 1930s, the German archaeologist Wilhelm Konig found a 14-cm (5-in) clay pot containing a copper cylinder. It was proven that the object was a kind of ancient battery.

But what intrigues researchers is the purpose of the artifact, dating back to 200 BCE. What did people at the time need batteries for? The exact age of the pots is also highly debated, as the style of the pots would belong to a later period, between the years of 225 and 640 CE.

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Voynich manuscript - Acquired by the rare book merchant Wilfrid Voynich in 1912, the manuscript included illustrations and diagrams. It seemed to describe different topics of herbal, astronomical, biological, and pharmaceutical nature.

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Voynich manuscript - The great mystery surrounding the manuscript is its unknown language, which has not yet been deciphered. What we do know is that the manuscript originated between the years 1404 and 1438.

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Voynich manuscript - After so many unsuccessful attempts to decipher the Voynich manuscript, many suggested that the manuscript was actually designed not to be deciphered.

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SS Ourang Medan - The mystery began when two American ships received a distress call in Morse code from the Dutch ship Ourang Medan. The event took place between June 1947 and February 1948 (the exact date is unknown).

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SS Ourang Medan - The message asked for help and said that the officers were dead. The ship Silver Star went to their rescue and when it got there they found the whole crew dead.

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SS Ourang Medan - Shocked at the sight of the dead, the Silver Star's captain towed the ship. But there was an explosion in the cargo area of the Ourang Medan, making it sink, and dragging any clues that could have helped solve the mystery of the dead crew to the bottom of the sea.

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SS Ourang Medan - One theory about the cause of the crew's death is that the Ourang Medan was carrying chemicals, which could have released gases that lead the crew to suffocate. Then, the movement caused by the towing eventually made the ship explode. There are others, however, who say that this story is nothing more than a legend, or rather, a fishermen's tale. Nothing has been proven to this day.

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Moai statues on Easter Island (Chile) - The small island hides a great mystery: around 887 Moai statues are scattered around the island, each one with an average height of 4 m (though 10-meter-high statues weighing up to 82 tons can also be found on the island!).

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Moai statues on Easter Island (Chile) - But what intrigues scientists most is how these stone monuments got there. Humans first settled on the island before 900 CE. How did they move these large and heavy statues with the limited resources they had at the time?

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Moai statues on Easter Island (Chile) - To try and recreate what may have happened, researchers have made replicas of the statues (with the same dimensions and weight) and used the methods and means available at the time, such as ropes, sleds, and human strength (in this case, hundreds of people dragging each Moai).

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Moai statues on Easter Island (Chile) - Despite advances in science, the Moai statues still remain an enigma to this day.

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Confederate gold (USA) - At the end of the American civil war, in 1865, when the Union army was heading for victory, a question arose among the Confederates: what to do with what was left of their gold?

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Confederate gold (USA) - In an attempt to preserve assets, Confederate Treasury Secretary George Trenholm liquidated the massive fortune. When they were finally captured, all the gold, silver, and jewels were gone.

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Confederate gold (USA) - Numerous theories have emerged about the vanished gold, for example, one of which includes the gold being distributed among plantation owners and buried in the region. However, no one really knows what happened.

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Dancing Plague (France) -

It sounds like fiction, but an epidemic happened in 1518 when a woman started dancing alone in the middle of the street for six days!

Suddenly, her behavior "infected" the crowd, and hundreds of people started dancing, continuing even when some of them died from exhaustion or heart attacks.

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Dancing Plague (France) - The epidemic stopped as mysteriously as it had started. After about one month of dance and death, people resumed their normal lives. Scholars have argued for centuries whether the epidemic, which was repeated in a few other cities, was a disease or a social phenomenon.

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Dancing Plague (France) - Research has pointed out that the "plague" appeared to be a type of cultural contagion, affecting extremely poor populations. But science has never been able to confirm what actually happened.

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Gobekli Tepe (Turkey) - The archaeological site, located on the top of a mountain in Turkey, is composed of more than 200 pillars, with a height of up to 6 m (20 ft) and weighing up to 20 tons, arranged in about 20 circles.

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Gobekli Tepe (Turkey) - Sculptures of animals (not native to the region), illegible hieroglyphs, ​​and various geometric forms were found on the structures. Scholars believe the place was built around 10,000 BCE.

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Gobekli Tepe (Turkey) - The main mystery is how the nomadic and neolithic civilization managed to organize a work force to erect a prehistoric site, and for what purpose would it have been built? Is this the oldest temple on the planet?

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Oak Island mystery (Canada) - Oak Island is informally known as "Money Pit," due to a well-like construction discovered in 1795. After over two centuries of excavations, the supposed hidden treasure has yet to be found.

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Oak Island mystery (Canada) - But what was discovered was also impressive. Beneath the surface of the well are a series of wooden platforms and flooding mechanisms formed through multiple underground channels leading to water.

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Oak Island mystery (Canada) - The first time anyone could dig deep enough, the entire well was immediately flooded. At the 90-ft (27 m) mark, a coded and inscribed stone tablet was discovered that said there were two million pounds 40 ft below. The problem is that nobody has got there!

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Antikythera mechanism (Greece) - In the early 20th century, a diver found a shipwreck near the island of Antikythera. Among the discovered objects were pieces of brass, which were part of an analog mechanism.

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Antikythera mechanism (Greece) - The device, which would work as a sort of analog computer, scientists say, would have been designed to determine the positions of celestial bodies using a complex series of brass gears.

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Antikythera mechanism (Greece) - The ingenious equipment would also have been created around 100 BCE. Despite these assumptions, the purpose and origin of the object has not yet been officially confirmed.

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Nazca Lines (Peru) - The lines were discovered in 1927 and declared a UNESCO World Heritage Site in 1994. The Peruvian pilot and archaeologist Toribio Mejia Xespe, who flew over the Nazca desert, was the first to spot the lines that formed these mysterious images.

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Nazca Lines (Peru) - There are more than 13,000 lines that form 800 figures, some that measure more than 65 km (40 miles) in length. Several theories about the origins of the lines and their purpose, some involving religion and even aliens, have been suggested.

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Nazca Lines (Peru) - The Swiss writer Erich Von Däniken said that the images could be a form of extraterrestrial communication. Archaeologist Maria Reiche, on the other hand, believed that the figures were linked to astrology (they would be constellations visible during specific times of the year).

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Nazca Lines (Peru) -

American researcher David Johnson defended that the lines would be indications of where water could be found in the desert subsoil. The German Markus Reindel and the Peruvian Johnny Isla, both archaeologists, saw the lines as places of offering for gods. Despite the many theories, science has never discovered the truth.

See also: The greatest discoveries and advancements in the history of astronomy

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