Do you believe in ghosts? Perhaps you were once in an empty house, you were alone in that room, yet your intuition told you that someone or something else was there with you. A creak on the stairway, the rustle of a curtain, a barely perceptible change in the air . . . if you had stopped and listened, what else would you have found or seen? From the gothic elegance of Powderham Castle in Devon, to the ruins of the Chateau de Lagnes in Provence, to...