Codex Trivulzianus
The Codex, that is held by the Trivulziana Library in the Sforza Castle, comprises a folder containing 55 sheets (measuring 20.5 x 14 cm), out of the original 62. Besides studies in architecture and religious themes, it contains numerous pages testifying to Leonardo's self-taught efforts to improve his literary education. Most of the pages date from between 1487 and 1490.