4. The Voynich Manuscript

The Voynich Manuscript is an illustrated, hand-written book that is in a completely unknown (possibly made up) language. There is no concrete evidence as to who wrote it, when it was written, or where it came from – only speculations. Carbon-dating of the pages puts it in the early 15th century, and historians speculate that it might have originated in Northern Italy. But regardless of the countless number of historians, cryptographers, and codebreakers who’ve studied the book, it remains a mystery to this day.