[2] The castle was first mentioned in the 12th century as the property of the Da Castello, a family from Novara.

[3] Enriched by duties on goods in transit along the river, the Visconti di Castelletto extended their dominions in the 15th century to the area surrounding the southern Lake Maggiore (Sesto Calende, Angera, Lisanza, Borgo Ticino, Pombia, Varallo Pombia, Invorio Superiore, Paruzzaro).

[4] The castle was renovated over the following centuries, mainly on the western side, and transformed into an aristocratic residence.

[4] Three types of masonry, probably related to different construction phases, are visible: river pebbles, squared stones, and plastered walls.

[1] Tommaso Grossi set some scenes of his historical novel Marco Visconti in the castle.