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

Leonardo da Vinci designed a keyboard instrument called the viola organista.

The instrument combined features of a keyboard and bowed string instruments. Pressing keys would bring rotating wheels or bows into contact with strings, producing sustained tones in a way that resembled the sound of a viola or other bowed instrument.

Leonardo drew several versions during the late 15th century, but no surviving original instrument is known. His sketches show his interest in using mechanical motion to reproduce musical effects that normally required a performer’s bow.

The viola organista should not be confused with a conventional organ, harpsichord, or piano. Modern builders have created working reconstructions from Leonardo’s drawings, but those instruments are interpretations rather than surviving Renaissance examples.