This one is a hard pill to swallow. Almost as hard as flying Indian Nuclear powered death machines.
The Voynich Manuscript is a book written in an unknown language in the 15th century, and has never been deciphered. It contains pictures and diagrams split into chapters like Astrology, Botany, Cosmology with extensive maps. No Big deal right? Tons of old maps and things have been found over the years.
Nothing in this book makes any sense whatsoever. The pictures of plants alone are enough to make your nose bleed, with pictures of trees with unknown fruit, star clusters that don't exist, maps and formations that have never ever been found to exist on our world. The writing is nothing like anything we have ever come across, and has not been translated as of yet. Tons of money has pumped into programs to have it translated and its diagrams deciphered to no avail.