These ancient Seeing-stones, made by Feanor, are the links that tie the Two Towers together. They allow communication between people across great distances, though they allow the user to manipulate what the other would see. One is in custody of Sauron, another with Saruman, and a third with Denethor in the White City of Minas Tirith. Sauron chose what the Steward would see, which showed the White City being razed to the ground. Eventually, Denethor went mad due to his Palantr.