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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There is a mysterious and loud radio signal known as 'the space roar' that has yet to be explained.
15
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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There is an island near Italy that was the site of wars, a dumping ground for plague victims, and an insane asylum. It's considered so dangerously haunted that the Italian government does not allow public access.
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