"By 1650, the spiritual and political power of the Catholic Church was shattered. Thanks to the twin blows of the Protestant Reformation and the Thirty Years War, Rome--celebrated both as the Eternal City and Caput Mundi (the head of the world)--had lost its preeminent place in Europe. Then a new Pope, Alexander VII, fired with religious zeal, political guile, and a mania for creating new architecture, determined to restore the prestige of his church...