 Camillo Borghese was born in Rome on 17 September 1550 into the Borghese family of Siena which had recently established itself in Rome.He was the eldest son of seven sons of the lawyer and Sienese patrician Marcantonio Borghese and his wife Flaminia Astalli, a Roman noblewoman.In June 1596 Camillo was made the Cardinal-Priest of Sant'Eusebio and the Cardinal Vicar of Rome by Pope Clement VIII, and had as his secretary Niccolò Alamanni.