Leonardo da Vinci designed the viola organista, a keyboard instrument whose strings are sounded by a rotating wheel.
Leonardo sketched the instrument in the late 15th century. Its keyboard operated mechanisms that pressed strings against a rotating, bow-like wheel, combining features of a string instrument and a keyboard. The design was never built by Leonardo, but later makers constructed working versions based on his drawings.
The viola organista is often confused with an ordinary organ because of its name and keyboard. It produces sound mechanically from strings rather than from pipes. It also differs from a hurdy-gurdy: a hurdy-gurdy uses a wheel turned by a crank, while Leonardo’s design was intended to let a player select notes from a keyboard.
The instrument illustrates Leonardo’s interest in mechanical systems, acoustics, and musical performance. Modern reconstructions show that the concept can produce bowed-string tones, although its historical operation remains dependent on interpreting incomplete Renaissance drawings.