Gian Giacomo, the eldest of fourteen children, was banished from Milan after a daring murder of revenge in broad daylight.
In the main church of Cima, which belongs to the community of Porlezza, an inconspicuous relief shows the lion of San Marco, a symbol of the alliance between Gian Giacomo de Medici and the former Republic of Venice.
It is likely that Gian Giacomo even had a residence in Cima, on the same spot where now stands a hotel, probably not called by chance Parco San Marco.
[2] In 1543 he purchased the ancient fortified castle of Frascarolo, near present-day Induno Olona, in the Valceresio, which he converted into a sumptuous villa.
Since his only son, Camillo (died after 1586), was illegitimate, albeit made a Knight of the Order of Malta, Gian Giacomo's honours passed to his brother Agosto (1501–1570).