Grosio (Italian pronunciation: [ˈɡrɔːzjo]; Lombard: Gros) is a comune (municipality) in the Province of Sondrio in the Italian region of Lombardy, located about 130 kilometres (81 mi) northeast of Milan and about 35 kilometres (22 mi) northeast of Sondrio, on the border with Switzerland.The municipality of Grosio contains the frazioni (subdivisions, mainly villages and hamlets) Tiolo, Vernuga and Ravoledo.Grosio borders the following municipalities: Grosotto, Monno, Poschiavo (Switzerland), Sondalo, Valdidentro, Valdisotto, Vezza d'Oglio.Grosio is twinned town with: