San Giulio Island or St. Julius Island is an island within Lake Orta in Piedmont, northwestern Italy. The island is 275 m long, and is 140 m wide. The most famous building on the island is the Basilica di San Giulio close to which is the monumental old seminary. Since 1976 it has been transformed into a Benedictine monastery.
The little island, just west of the lakeshore village of Orta San Giulio, has very picturesque buildings and takes its name from a local patron saint, who lived in the second half of the 4th century. The Church of San Giulio, Castellanza, which is located in Castellanza, Varese, northern Italy, was named after the island.