View a larger slideshow A brutal murder, a nefarious plot, a coded letter. After five hundred years, the most notorious mystery of the Renaissance is finally solved. Book Details | Author Bio | Praise | Read an Excerpt

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Marcello Simonetta, working in a private archive in Italy, stumbled upon a coded letter written by Federico da Montefeltro, the Duke of Urbino, to Pope Sixtus IV. Using a codebook written by Cicco Simonetta to crack its secrets, the author unearthed proof of an all-out power grab by the Pope for control of Florence. These are images of the coded letter from Federico da Montefeltro to his envoys in Rome.