Mozart and his sister Maria Anna started performing together publicly in 1764; they were probably the first ever to play piano four-hands in Europe, for which Mozart also composed the first pieces. Further sonatas and one set of variations followed in Salzburg (KV 358 and KV 381) and Vienna (KV 497, KV 501 and KV 521). The Sonata in D, KV 448 and the Fugue in C minor, KV 426 are Mozart’s only completed compositions for two pianos without orchestral accompaniment.