medieval:

The Voynich manuscript, described as “the world’s most mysterious manuscript”, is a work which dates to the early 15th century, possibly from northern Italy. It is named after the book dealer Wilfrid Voynich, who purchased it in 1912.

Now available in its entirety at Yale’s Beinecke Rare Book Library.

I don’t know how to explain to you how fascinating I find this book. Beinecke Library, I love you.