From John Baez:
The Voynich manuscript is by far the most mysterious of all texts. It is seven by ten inches in size, and about 200 pages long. It is made of soft, light-brown vellum. It is written in a flowing cursive script in alphabet that has never been seen elsewhere. Nobody knows what it means. During World War II some of the top military code-breakers in America tried to decipher it, but failed. A professor at the University of Pennsylvania seems to have gone insane trying to figure it out. Though the manuscript was found in Italy, statistical analyses show the text is completely different in character from any European language.