The publication analyses the large number of documents related to the history of the organs of the Duomo di Guastalla, conducted by Federico Lorenzani and Andrea Carmeli. It all begins around 1585 with the building of the first organ, probably by the famous Vincenzo Colonna. Part of this original pipework has been reused in the latter rebuilding by Giuseppe Bonatti in 1726-27 and in the present two manuals instrument by Giuseppe II Serassi in 1792-94, which has made it to the present day in exceptional original conditions. Among the documents hereby published, the registration methods by Bonatti (the only known one by him) and by Serassi, as well as an interesting correspondence made of 20 letters by Giuseppe Serassi to the clergy of Guastalla. The publication contains also an analysis of the pipework by Maurizio Isabella and a detailed report over the 1978 and 2018 restorations by Mascioni, with an impressive photo gallery taken in both occasions. Moreover, a comprehensive essay by Adriano Giacometto traces down the peculiarities of the two manual instruments made by Serassi in 18th century. The publication is then completed by an analysis made by Francesca Benevelli about the different position of the organ over the centuries and by a report overe the restoration of the magnificent case, conducted by Ilenia Nicoli.