At the turn of the 16th century, Italy was a turbulent territory made up of independent states, each at war with or intriguing against its neighbor. There were the proud, cultivated, and degenerate Sforzas in Milan, and in Rome, the corrupt Spanish family of the Borgia whose head, Rodrigo, ascended to St Peter's throne as Pope Alexander VI. In Florence, a golden age of culture and sophistication ended with the death of the greatest of the Medici family,...