Leonardo da Vinci designed the viola organista as a stringed keyboard instrument.
The concept combined a keyboard with a continuously rotating wheel or wheels that rubbed against strings, producing a sustained bowed sound. Pressing keys selected the strings, while the wheel supplied the friction normally created by a violin bow.
Leonardo drew several versions of the instrument in his notebooks during the late fifteenth and early sixteenth centuries. No confirmed original instrument built by Leonardo survives, and the design was never a mainstream Renaissance instrument.
The viola organista is often confused with a conventional keyboard such as a harpsichord. Unlike a harpsichord, which plucks strings, Leonardo’s design attempted to bow strings mechanically. Modern builders have reconstructed versions based on his drawings.