Leonardo da Vinci designed the keyboard string instrument known as the viola organista.
The viola organista combines features of a keyboard and a bowed string instrument. Pressing keys selects pitches, while a rotating mechanism rubs continuously moving bowing surfaces against the strings. This arrangement was intended to let one player produce sustained, bowed-string sounds through a keyboard.
Leonardo drew several versions of the idea in his notebooks, but no surviving evidence proves that he completed a working instrument. The design belongs to his long-running interest in musical acoustics, mechanical systems, and instruments for court entertainment.
The viola organista should not be confused with a standard viola, which is played with a hand-held bow, or with an organ, whose pipes produce sound from air. Modern builders have created reconstructions, including one made by Polish musician Sławomir Zubrzycki and unveiled in 2013.