Leonardo da Vinci designed the viola organista as a Renaissance instrument with bowed strings operated by keys.
Leonardo sketched the concept in the Codex Atlanticus and other notebooks during the late fifteenth century. Pressing a key was intended to bring a string into contact with a continuously rotating wheel or belt, producing a sustained bowed sound. The design combined keyboard control with the sound-producing principle of a bowed string instrument.
The viola organista is often described as a hybrid of a piano, organ, and string ensemble, but it was not a conventional organ because its sound came from strings rather than pipes. It also was not the same as a hurdy-gurdy, whose wheel is turned by a hand crank while keys shorten the strings.
No fully working Leonardo original survives. Modern builders have constructed instruments based on his drawings, and these reconstructions show how his mechanical ideas could be applied to musical performance. The instrument is historically important because it demonstrates Leonardo’s interest in linking engineering, acoustics, and practical design.