Mazzo di Valtellina is a comune in the Province of Sondrio in Lombardy, about 120 kilometres northeast of Milan. As of 1 January 2021 the es…Mazzo di Valtellina is a comune in the Province of Sondrio in Lombardy, about 120 kilometres northeast of Milan. As of 1 January 2021 the estimated population was 1,017. Mazzo is in the upper part of Valtellina in an area of primary importance: laying at the foot of the Mortirolo Pass, it allowed easy access to the Valcamonica valley and subsequently to the territories of the Republic of Venice, which had strategic interests in trade with the German-speaking countries.