The Voynich Manuscript

 The Voynich manuscript is an illustrated codex hand-written in an unknown writing system.
All attempts at deciphering its contents have been unsuccessful. And it's not like some idiot just scribbled a bunch of nonsense on paper it is actually an organized book with a consistent script, discernible organization and detailed illustrations.The text is written from left to right, and most of the pages have illustrations or diagrams.

Back in 1912 in a crumbling Jesuit college near Rome, an antiquarian bookseller called Wilfrid Voynich bought a mysterious enciphered handwritten book. Despite its length ( Some of the pages are missing, but about 240 remain) it was an ugly, badly-painted little thing, for sure: but its strange text and drawings caught his imagination — and that was that.

It appears to be a real language--just one that nobody has seen before. And it really does appear to mean something. But nobody knows what.