Leonardo da Vinci designed the viola organista, a keyboard instrument played by rotating bowed wheels.
The concept appears in Leonardo’s notebooks from the late fifteenth and early sixteenth centuries. Pressing keys would bring strings into contact with continuously rotating wheels, producing sustained tones in a way that combined features of a keyboard and a bowed string instrument.
Leonardo explored several versions, and the surviving drawings show that the design changed over time. Unlike a conventional violin, the player would not move a bow back and forth by hand. Instead, the wheel supplied the friction needed to make the strings sound.
No authenticated instrument built by Leonardo survives. Modern instrument makers have constructed playable interpretations from his drawings, including a version completed by Polish musician Sławomir Zubrzycki in 2012. The viola organista is therefore best understood as an ingenious Renaissance instrument concept.