He was born at
Florence, the second son and third child of
Cosimo II de' Medici, Grand Duke of Tuscany and
Maria Maddalena of Austria. He entered the ecclesiastical state at a young age. In 1620 he joined the
Sovereign Military Order of Malta and was named Grand Prior of Pisa. In 1638 he was named General of the Mediterranean Sea. On 14 November 1644
Pope Innocent X created Giancarlo a cardinal-deacon as a token of his affection toward the
Medici. Thus forced to give up his military career and with it the title of "General of the Spanish Seas", Giancarlo could not reconcile himself to his new "religious" lifestyle. Cardinal de' Medici participated in the
papal conclave, 1655 as one of leaders of the Spanish faction.
Pope Alexander VII made Giancarlo responsible for welcoming
Queen Christina of Sweden, a new convert to Catholicism, to Rome in 1655. Upon discovering of the closeness that had formed between the two, the Pope sent Gian Carlo back to Florence, declaring him "too handsome and too young" to be "spiritual advisor" to the Queen. Here, Giancarlo led a life of dissipation, taking many mistresses; nevertheless, Ferdinando II delegated to him the management of the state's financial affairs. After one of his mistresses died, "the sexton who buried her said that Cardinal Gian Carlo, remembering the convulsions of that ivory body, came to look once more; and overcome by so much beauty, entered the vault and lay with her for the last time." He murdered a romantic rival, Cavaliere Luna, but his brother, Duke Ferdinando II, did nothing. He was patron of science, letters and music. He founded the
Accademia degli Immobili and contributed to the construction of
Teatro della Pergola and the enrichment of the
Galleria Palatina di Palazzo Pitti. In later years, Giancarlo donated his sizeable art collection to form the
Pitti Gallery. He died at Florence, of an
apoplexy, at the age of 51, and was interred in the
Medicean necropolis,
the Basilica of San Lorenzo,
Florence. Four years after the death of Giancarlo, his younger brother
Leopoldo was created a cardinal. ==Ancestors==