Francesco Abbondio Castiglioni was born in Milan on February 1, 1523, and was the son of Palatine Count Girolamo Castiglioni and Guida Francesca Castiglioni.[1] He was himself a palatine count and a Milanese patrician.[1] Early in his life, he studied Latin and Greek.[1] He later attended the University of Pavia, where he studied Christian theology, poetry, canon law, and civil law.[1]
He began his career in the church as a cleric in Milan.[1] Originally named Francesco Castiglioni, he took Abbondio as a middle name when he was named commendatory abbot of Sant'Abbondio in 1551.[1]
On January 9, 1562, he was elected Bishop of Bobbio and he was subsequently consecrated as a bishop.[1] He participated in the Council of Trent 1562-63.[1]
Pope Pius IV made him a cardinal deacon in the consistory of March 12, 1565.[1] He participated in the papal conclave of 1565-66 that elected Pope Pius V.[1] He received the red hat and the deaconry of San Nicola fra le Immagini (a titular church given the status of deaconry pro illa vice) on February 8, 1566.[1]
He died in Rome on November 14, 1568.[1] He was buried in the Montemirabile Chapel in Santa Maria del Popolo.[1]
