Alva Smith, her southern family destitute after the Civil War, married into one of America's great Gilded Age dynasties: the newly wealthy but socially shunned Vanderbilts. Ignored by New York's old-money circles and determined to win respect, she designed and built nine mansions, hosted grand balls, and arranged for her daughter to marry a duke. But Alva also defied convention for women of her time, asserting power within her marriage and becoming...