Fantasia in C minor, K. 475

Fantasia in C minor, K. 475 is a piece of music for solo piano composed by Wolfgang Amadeus Mozart in Vienna on 20 May 1785. It was published as Opus 11, in December 1785, together with the Sonata in C minor, K. 457, the only one of Mozart's piano sonatas to be published together with a work of a different genre.
Starting in the key of C minor, the piece is marked "Adagio" but then, after a section in D major, moves into an "allegro" section which goes from A minor to G minor, F major, and then F minor. It then moves into a fourth section in B major marked "Andantino" and then moves to a "più allegro" section starting in G minor and modulating through many keys before the opening theme returns in the original key of C minor. Most of the music is written with no sharps or flats in the key signature and uses accidentals—only the fourth section, in B major, is given a key signature.