In 1506, Michelangelo--a young but already renowned sculptor--is invited by the Sultan of Constantinople to design a bridge over the Golden Horn. The sultan has offered, alongside an enormous payment, the promise of immortality, since Leonardo da Vinci's design had been rejected: "You will surpass him in glory if you accept, for you will succeed where he has failed, and you will give the world a monument without equal." Michelangelo, after...