 Between 1242 and 1248, on the site of the old chapel, he built the Sainte-Chapelle shortly before he departed for the Seventh Crusade.It housed the sacred relics Louis had acquired, which were believed to be the crown of thorns and wood from the cross of the Crucifixion of Christ, purchased in 1238 from the governor of Constantinople.These symbols allowed Louis to present himself not just as the king of France, but as the leader of the Christian world.