Basilica di San Giulio, Romanesque minor basilica on San Giulio Island, Lake Orta, Italy

The Basilica di San Giulio is a Romanesque church on San Giulio Island in Lake Orta with three naves, semicircular apses, and cross vaults. Two bell towers flank the main facade with narrow window openings and double-arched lancets.

According to tradition, Julius of Novara founded a small church on the island around 390. Excavations revealed a 5th–6th century chapel with a single north-facing apse, replaced about a century later by a larger church. After the sieges of 956 and 962, Otto I donated lands and rights that funded reconstruction. The present three-nave Romanesque church was built in the 12th century on the model of Novara Cathedral.

The 12th-century ambon is carved from grey-green serpentine from the Oira quarry and rests on four older columns, two smooth and two twisted, with capitals of leaves and animal heads. On the parapet, read counter-clockwise, a centaur hunts a deer, the four Evangelist symbols appear, and a griffin bites a crocodile's tail. A male figure may be William of Volpiano, born on the island in 962.

The church houses a museum section near the crypt displaying ancient artifacts and informational panels about construction phases. Visitors can follow the different building stages of the island church through the displayed materials and explanations.

The octagonal lantern over the crossing survives from the Romanesque phase, though it was altered in the late 18th century: each side received a window except one, which kept its blind trifora with slender columns and foliate capitals. The bell tower stands apart from the church, close to the apses, and its style resembles that of the Abbey of Fruttuaria.