Codex Leicester: the world's bestselling book

"The Codex Leicester, written by Leonardo da Vinci, is considered the most expensive book sold in the world, with a starting price of $30.8 million. The inflation-adjusted price is $54.4 million.

According to sources, the most expensive book ever sold is Codex Leicester, which Bill Gates bought in 1994 for $30.8 million and in 2021 is worth around $54.4 million.

What makes the book unique is that the Codex Leicester was Leonardo da Vinci's scientific diary. Created in 1510, it contains Da Vinci's drawings, theories and observations on information such as the movement of water, the brightness of the moon and why fossils of sea creatures can be found in the mountains.

Gates also reportedly scanned the Codex digitally after purchasing it, releasing some images as screensavers and wallpaper for Windows 98 Plus.