Two of the great ceremonial halls still remain within the structure of the Palais de Justice. He also built a more sinister structure, the Gibbet of Montfaucon, near the modern Place du Colonel Fabien and the Parc des Buttes Chaumont, where the corpses of executed criminals were displayed. On 13 October 1307, he used his royal power to arrest the members of the Knights Templar, who, he felt, had grown too powerful, and on 18 March 1314, he had the Grand Master of the Order, Jacques de Molay, burned at the stake on the western point of the Île de la Cité.[37]