The Codex Leicester

The Codex Leicester must be one of the most valuable notebooks in the world. It is the notebook of none other than Leonardo da Vinci and contains a collection of handwritten scientific writings, observations, and theories about a few different topics such as the explanation of why fossils of sea creatures can be found in the mountains, the movement of water and the luminosity of the moon. The notebook was leather-bound but its pages are now displayed separately and it includes exceptional illustrations by the artist showing the link between art and science.

It was first purchased in 1717 by Thomas Coke who later on became the 1st Earl of Leicester and therefore influenced the name we know now. Armand Hammer was the owner of the notebook after Earl and briefly renamed it, Codex Hammer. From 1980 the notebook stayed in Hammers' possession for 14 years and then in 1994 it was nabbed at auction by Bill Gates for a jaw-dropping $30.8 million!