Lake orta is a subalpine lake in Piedmont, between the provinces of Novara and Verbania. In the middle ages it was known as San Giulio's lake, and it was only at the beginning of the XVII century that the name Lake Orta, from the main town on the lake, started to spread. The ancient name "cusius" comes from an incorrect reading of the "tabula peutingeriana" where we can find a lacus Clisius, still unidentified.
The historian Lazzaro Agostino Cotta, author of a famous study on lake Orta and surroundings, started using the name Cusio, that we can find in both learned and administrative texts, and it is still used nowadays referring to the lake. On the other hand it is only a legend that this name could come from a fantastic tribe called "Usii", appearing for the first time in some writings of the historian Antonio Rusconi around the year 1880.
Lake Orta is surrounded by mountains, separating it to the east from lake Maggiore with mount Mottarone and to the west from the Valsesia Valley. It is the most western between the great subalpine lakes, and it was created from the southern part of the Simplon glacier. Differently from the majority of alpine lakes, that have an outflowing river towards south, Lake Orta waters flow northbound, with the small river Nigoglia in the city of Omegna and then into the river Toce and lake Maggiore. In the middle of the lake there is the beautiful small island of San Giulio, with a Basilica and the relics of the Saint who gives his name to the island.