This instrument is one of the rarest original pianofortes built in Portugal that survived until today, being, therefore, one of the most relevant items of the Museum's collection. Van Casteel was a maker of Belgian origin who exercised his trade in Portugal between about 1757 and 1769. This instrument is currently the only known Casteel pianoforte in the whole world. In addition to this instrument, there is only one more known of his authorship: a late 18th century pyramid piano, belonging to the Musée des Instruments de Musique, in Brussels.