Historiographical tradition links the adventures of Angera to the Visconti family, who originated from the Verbano region and, in particular to the victory in 1277 of Ottone Visconti over the Della Torre or Torriani. Its strategic position, which favoured control of traffic on the lake, made it very important for the entire period of the Middle Ages. Under the Visconti, Angera Fortress was at the centre of important reconstruction and extension work that lasted for over a century. During the Ambrosiana Republic (1447-1450), the Consiglio dei Novecento (Council of the Nine hundred) of the city of Milan sanctioned the purchase of the fortress by Vitaliano I Borromeo for the sum of 12,800 Imperial Lire. The fortress thus became the usual place of residence and the symbol of the family's political order. Subsequent years were very conflicting for the fortress and it became the object of contention between the Borromeo and Sforza families. Only in 1449 was the fortress finally returned to the Borromeo family who still own it to this day and, who are responsible for carrying out the main interventions undertaken from the fifteenth century onwards.