Scientists lit a cave of natural gas on fire in 1971 expecting it to only burn for a few days; it still burns to this day. It has been nicknamed "The Door to Hell".
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In 1518, a "dancing plague" struck Strasbourg, Alsace, whereby hundreds of people danced fervently in the streets over the period of a month. Some suffered heart attacks or strokes, and many others died from sheer exhaustion. It remains unexplained.
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There is a 600 year old 240 paged book called the Voynich Manuscript, that’s written language is still completely unknown today.
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In 1987, a Chicago TV station had its broadcast interrupted by a pirate signal that shows a man in a Max Headroom mask mumbling and being spanked with a fly swatter. Despite investigations by the FCC and FBI, this became the only known incident in which a hacker interrupted a major TV broadcast without getting caught.
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There is a mysterious and loud radio signal known as 'the space roar' that has yet to be explained.
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There are pictures of Knights fighting Snails in old Medieval manuscripts - and nobody knows why.
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