What musical instrument did Leonardo da Vinci invent with strings and keyboard keys?

Leonardo da Vinci invented the viola organista, a keyboard instrument with bowed strings.

The instrument appears in Leonardo’s notebooks and was designed to combine the controllable keys of a keyboard with the sustained sound of bowed strings. Pressing keys would bring rotating wheels or a continuous bowing mechanism into contact with strings, producing tones without requiring the player to hold a conventional bow.

Leonardo made several related drawings, and the exact construction details vary between surviving designs. The instrument was not widely adopted during his lifetime, so it did not become a standard member of the Renaissance orchestra. Its unusual mechanism nevertheless shows Leonardo applying mechanical engineering to musical problems.

The viola organista is sometimes confused with a hurdy-gurdy because both use friction to sound strings. A hurdy-gurdy is turned by a crank and played with keys, whereas Leonardo’s concept was specifically arranged as a keyboard instrument. Modern builders have produced working reconstructions from his drawings.