Reprint of the work dedicated to the mighty feudal House of Vicedomini from Como, episcopal vassals known since the X century, which posseded as Imperial fief the area more or less corresponding to the Terziere Inferiore of the Valtellina, and soon subdivided in two main branches of different political allegiance, respectively living in the castles of Cosio and Domofole. This essay was first published in the Archivio Storico della Svizzera Italiana in 1936, and takes profit, along with those conserved in public collections, from the parchements in the family archive of the author, inherited through the House of Paravicini from the branch of the Vicedominis died out in Dazio in the Eighteenth century.