The Sainte-Chapelle, also known as the royal chapel of the Île de la Cité, is a Gothic church located on the Île de la Cité. It is considered one of the crowning works of the radiant period of Gothic architecture. It was built to house the relics acquired by King Saint Louis of France, including the crown of thorns, which is why it has been considered an enormous reliquary. Thanks to the innovations of the Gothic construction system, there are practically no wall supports (walls), and instead there are a multitude of openings (windows) that filter light through the polychrome stained-glass windows.

The history of the chapel begins in 1241 when the crown of thorns, part of the cross, the iron lance of Longinus, the sponge and other relics of the martyrdom of Jesus Christ, which had been acquired by King Louis IX from Baldwin II, the last Latin emperor of Constantinople, were brought to France from Syria and Constantinople. The French king came to receive these holy relics and he himself entered Paris with them, barefoot, depositing them temporarily in the chapel of Saint Nicholas in his palace, until a chapel worthy of the relics could be built. The Sainte-Chapelle was probably begun in 1241 and consecrated in 1248.