His cult is centred at Lake Orta in the Novarese highlands, and in particular on the island which has been named for him since at least the eighth century,[2] Isola San Giulio, and where his presumed relics are preserved in the crypt, called scurolo, of a basilica dedicated to him.

In the earliest Vita, which dates from no earlier than the eighth century and is of a character as much legendary as historical, the account of his life is interlaced with that of his brother Julian (Giuliano), a deacon whose name is similar enough to suggest that they may have been the same person, but now we know (thanks to recent archaeological finds in Gozzano's previous parish church, S. Lorenzo) that they both existed.

They are said to have been ordered by Theodosius I to destroy pagan altars and sacred woods and to build Christian churches.

The ninety-ninth church is said to have been built at Gozzano, and dedicated to Saint Lawrence.

The hundredth church was built by Julius on the island that bears his name; he dedicated it to Saints Peter and Paul.