A Synopsis by Franco Baseggio
The family originated in Rome and emigrated to Venice and Trieste in the years before 1000. It is not clear whether the emigration was to Trieste first and then to Venice, or vice versa, or to both cities independently. There are also Baseggios who emigrated to Padua in that same era and Baseggios are considered to be one of the founding families of all three cities.
Beginning in the 13th century, Baseggios from Trieste emigrated to Capodistria, Gradisca and Pinguente, in what is now Slovenia. From there they returned to Italy in the 18th and 19th centuries. One minor branch apparently emigrated to Greece during the time of the Crusades. Those branches that remained in Italy are found mostly in Venice, Trieste and Treviso.
Beginning in the 19th century, various branches emigrated to various parts of the world. As of today, large groups can be found in Brazil, Australia and the United States. Smaller concentrations are known to exist in Switzerland, Belgium, France, Greece, Uruguay, Argentina and Africa.
Sources: "History of Trieste" by Father Ireneo of the Cross, "Il Cappellari", Campidoglio Veneto, "Genealogie delle Tredici Casate" by Luigi de Jenner, "Le Tredici Casate" by Sergio Sghedoni and Marco Dorian.