Orta San Giulio is a town and comune in the Province of Novara in the Italian region of Piedmont, located about 100 kilometres northeast of Turin and about 40 kilometres northwest of Novara. It is one of I Borghi più belli d'Italia. The town itself is built on a promontory which juts out from the eastern bank of Lake Orta close to San Giulio Island, an island which also falls within the municipal boundaries.