For which Milanese ruler did Leonardo da Vinci design a revolving bridge?

Leonardo da Vinci designed a revolving bridge for Ludovico Sforza, the ruler of Milan.

Leonardo entered Ludovico Sforza’s service in Milan in 1482 and presented himself as an engineer, architect, and military specialist as well as an artist. His revolving bridge concept was intended to combine rapid deployment with the ability to move troops or cross waterways. A pivoting structure could be swung into position and then cleared away when necessary.

The bridge belongs to Leonardo’s extensive engineering notebooks, which include canals, fortifications, weapons, and machines for lifting or transporting materials. The surviving drawings reveal how he studied practical movement rather than treating a bridge as a static structure only.

The design is sometimes confused with Leonardo’s self-supporting or temporary bridges. Those are related but distinct proposals. The ruler named in connection with the revolving bridge is Ludovico Sforza, also known as Ludovico il Moro, who controlled Milan during Leonardo’s major Milanese period.