A lament played by a bow

Exploration Stage: Enchanted Ball
From: Martha
Description: I have gathered excellent dances for Juliette, but how can I ask her to dance without music? To fulfill the ghost's request and free Juliette, we need to collect the instruments used in the best orchestra this city has ever seen. You must find the violin inside the ballroom. This instrument is called the queen of orchestras.
Completed: What a stunning old violin. Look at it. It is inscribed by the famous master craftsman Guarneri. If I am not mistaken, it is the very same one used by Niccolò Paganini!