Guglielmo Quarenghi (Casalmaggiore, October 22, 1826 – Milan, February 3, 1882) was a major 19th-century Italian cellist. A composer and a performer, as well as a main figure of the Milan musical scene, he was first cello at the Scala Theater Orchestra and taught at the Royal Conservatory, Milan, thus carrying forth the tradition embodied by Giuseppe Sturioni and Vincenzo Merighi, who also held both positions and can rightly be seen as founders of the Lombard cello school.
Quarenghi wrote extensively for his instrument and published a comprehensive five-part treatise, for which he is mostly remembered today. Issued by Editoria Musicale, Milan, in monthly installments between 1877 and 1879, and subsequently by Ricordi, the Metodo di Violoncello, introduced by Alfredo Piatti and evaluated by a panel of authorities, was approved and adopted by the Milan Conservatory. Quarenghi's fame then spread outside Italy and Europe.
The Metodo is a document of enormous musicological value. It opens up new perspectives on period performance practice for its breadth of conception, and above all for the inclusion of a unique chapter on cello performance of figured bass under opera recitatives.