On the northeastern side, a wall with corner turrets extends outside the building and bends towards the lake until the edge of the cliff enclosing a garden.

The tower belonged to the Milanese church, and in the 13th century, it was the refuge of Archbishop Leone da Perego after being forced to flee Milan by the city faction led by the Della Torre family.

[2][6] The Della Torre were defeated by the Visconti family, leader of the party of the Milanese nobility, in the battle of Desio in 1277.

[9] The Ottonian wing contains the Hall of Justice, decorated by an unknown painter with frescoes representing episodes from the life of Archbishop Ottone Visconti, his victory against the Della Torre, and the subsequent pacification of Milan.

They underline the magnanimity of Ottone Visconti and his will to peacefully obtain the city's government, as shown by the constant presence of the Christian cross above his head.

A wall, whose frescoes have partly survived, shows the Wheel of Fortune to symbolize the alternation of events that saw the Della Torre pass from dominating the city of Milan to their defeat.

Initially, Gaspare Visconti of Uberto, a powerful count of nearby Arona and a distant cousin of the dukes, took advantage of it, obtaining rights over Angera town and perhaps its castle.