Born without a dowry, nearly forced into a convent, and later married off to a man she didn't love, Olimpia Maidalchini vowed never to be poor, powerless, or beholden to any man again. Instead, using her wits, Olimpia became the unofficial ruler of the most powerful institution in the world: the Roman Catholic Church. The Church firmly states that women must be excluded from church leadership positionsbut for more than a decade in the seventeenth century, Olimpia ran the Vatican. As sister-in-law and reputed mistress of the indecisive Pope Innocent X, she appointed cardinals, negotiated with foreign ambassadors, and helped herself to a heaping portion of the Papal States' treasury.In Mistress of the Vatican, New York Times bestselling author Eleanor Herman brings to life not only an extraordinary woman lost in history but an entire civilization in all its greatness . . . and ignominy. This is the unforgettable story of a woman ahead of her time.