Over the course of the centuries various architects and designers have been involved with and enthralled by the castle and its defensive architecture, including Leonardo da Vinci, who was called to Milan by Ludovico il Moro in 1482. The Tuscan genius' interest in civil and military architecture is well documented in both his notes and sketches. Two drawings in particular (Manuscript B, Institut de France, Paris; Vallardi Codex, 2282, Louvre, Départment des Arts Graphiques, Paris) attest to Leonardo's reinvention of fortified structures for the Milanese fortress.