Tratto da:
Il Castello di Milano

Castle of Milan
Period of the Viscontis
Di Baio Editore

1368
Foundation of the Viscontis’ castle, called the Castle of Porta Giovia (horn the name of the nearest gate of the town) by order of Galeazzo II Visconti, who, after having poisoned, so it is rumoured, his brother Matteo II, Signore of Milan, had divided the Signoria with his other brother Bernabò, his accomplice.
1378 Death of Galeazzo II - His son Gian Galeazzo succeeds him and shares the Duchy with his uncle Bernabò though making Pavia his residence.
1385 Gian Galeazzo, who had for years pretended to be quite inept so as to deceive his uncle and fatherin-law feigns to go on a pilgrimage to Varese with a great retinue of soldiers, and invites Bernabò to meet him. Having found him outside the Pusterla of Sant’Arnbrogio
where the other had gone to wait for him Galeazzo has him and his son treacherously arrested by Jacopo dal Verme and Ottone Bandello.
Bernabò is kept a prisoner for a while in the Castle of Porta Giovia, and is then taken to the Castle of Trezzo where a few months later he dies, it is said by poison.