Leonardo da Vinci invented the viola organista, a stringed keyboard instrument.
The viola organista combined a keyboard with bowed strings. Pressing a key was intended to bring a rotating wheel or belt into contact with strings, producing sound in a way related to bowed string instruments. Leonardo explored several versions of the idea in his notebooks, rather than leaving one finalized production model.
The instrument was intended to offer the player keyboard control while retaining a sustained, violin-like tone. It was technically complex because the mechanism needed to coordinate the keyboard, moving bowing surface, and strings with enough precision to produce consistent notes.
Leonardo’s viola organista should not be confused with a conventional piano, harpsichord, or organ. Those instruments produce sound through different mechanisms. Modern builders have constructed playable versions based on Leonardo’s drawings, but no authenticated original instrument by Leonardo is known to survive.