Most Expensive Book/Manuscript: Codex Leicester (Codex Hammer), Leonardo Da Vinci

Price: $30,800,000

Codex Leicester was written around 1508, and is one of 30 or so similar books produced by Da Vinci across his lifetime. Within the Codex Leicester’s 72 loose pages are around 300 notes and detailed drawings rendered in chalk and brown ink, alongside Leonardo’s famed ‘mirror writing’. All of these sketches are based around a common theme: water and how it moved. Codex Leicester’s historical importance is further bolstered by the fact that Da Vinci is thought to have used its contents as research to paint the background of his masterwork, the Mona Lisa.