Just learned about the Voynich Manuscript, a handwritten book apparently dating back to at least the seventeenth century. But it's in a weird, unidentifiable script that has so far resisted all attempts to decipher or decrypt it, and it contains (among other things) drawings of plants which look wholly unlike anything currently known.
Go here to see high-quality black-and-white scans of some of the pages; type "ms 408" into the search box.
As an aside, the instructions for the search box contain the sentence Use single apostrophe's within words where appropriate. Ironically, as Bob the Angry Flower teaches us, the use of an apostrophe to indicate a plural is inappropriate.