Check this out: a collection of music from the 15th century was recently found in a pile of art in Brussels.
This book, known as the Leuven Chansonnier, is one of six fifteenth-century songbooks known to exist, and the first one that has been discovered in more than a century. Musicologists will be studying both the physical item and the music contained within it. As one researcher observed, this discovery is: “Unbelievable. It’s like suddenly finding a dozen new drawings by Rubens"
This old book of music is also just a beautiful item, which has already been scanned so that you can see it online.