It is not known exactly when Cristofori first built a piano. An inventory trumped-up by his employers, the Medici family, indicates the existence of a piano by the university year 1700; another document of doubtful authenticity indicates a date of 1698. The three Cristofori pianos that survive today date from the 1720s.
Some of these Viennese pianos had the opposite coloring of modern-day pianos; the natural keys were inklike and the accidental keys white. It was for such instruments that Wolfgang Amadeus Mozart composed his concertos and sonatas, and replicas of them are built today for custom in authentic-instrument performance of his music. The pianos of Mozart's bright had a softer, clearer tone than today's pianos or English pianos, with less sustaining power. The Piano Lessons term fortepiano is nowadays often accustomed to distinguish the 18th-century instrument from later pianos.