Rediscovered in 1966 together with Codex Madrid I, this manuscript contains a miscellaneous range of drawing types, including coloured maps of the Arno, relating to the Florentine project to bypass the unnavigable sections of the river.

The manuscript also contains important notes and drawings relating to the casting of the Sforza horse. Passages from this manuscript were accurately transcribed by Francesco Melzi and put into the Codex Urbinas to form part of the treatise on Painting.