Other objects of interest are found in the chapels along the nave and transept. The initial impetus for the building of the cathedral came from the installation of the reputed head of John the Baptist on 17 December 1206. The head was part of the loot of the Fourth Crusade, which had been diverted from campaigning against the Turks to the sacking of Constantinople, the capital of the Byzantine Empire. A sumptuous reliquary, with the face of the Saint, was made to house the skull. Although the skull and original reliquary were lost during the Revolution, a 19th-century replica was made and is displayed on the north aisle.