20. Cesare contracted syphilis at the age of 22, and had to wear a mask later in life to hide his disfigurement
One of Cesare’s final acts as Cardinal was crowning the King of Naples. According to Machiavelli, after carrying out his duty the 22-year-old Cesare hired a prostitute. Shining a lamp on the woman after having sex, the horrified Cesare discovered she was a grotesque, toothless crone. He instantly vomited on his lover, but she left him with more than just nausea. The prostitute gave Cesare syphilis, a horrible STD that rots the flesh and causes hideous disfigurement. Cesare was never cured, and in later life wore a mask in public to hide his mutilated face.