St. Chapelle, at 6 boulevard du Palais, is now surrounded by the Palace of Justice on the Ile de la Cite, Paris, near Notre Dame. It was built as a palatine chapel for King Louis IX of France (known as St. Louis, reigned 1226 1270) between 1242 and 1247, and consecrated on 26 April 1248. During Louis IXs reign, Gothic architecture in France entered the rayonnant phase, its name derived from the radiating spokes of the large rose windows that characterized the style. Refining the stone-framed architecture of the age, architects further reduced the amount of solid wall in favor of expansive traceried stained-glass windows. The masonry that remained was in the form of narrow but very thick buttresses that dealt with the thrusts imposed by vaulted stone ceilings. St. Chapelle, with its luminous glass curtains, represents the highest degree of this structural refinement and is probably the most beautiful surviving example of the French Gothic of any phase.
In 1239 Louis IX purchased (at extravagant cost) a number of relics of the crucifixion of Christ from his bankrupt cousin, Jean de Brienne, the Emperor of Constantinople. The most important of them was the crown of thorns; there was also a piece of iron from the lance used by the soldiers and the sponge on which Jesus was offered sour wine. From de Briennes successor, Baudouin II, Louis bought a piece of the true cross. To purchase them and fashion a reliquary a bejeweled chest that was destroyed during the French Revolution it is said that Louis spent two and a half times what it cost to build St. Chapelle. Soon after acquiring the relics, he commissioned a private chapel within the royal palace on the Ile de la Cite to hold them. There is some debate about the identity of the architect; many sources identify Pierre de Montreuil, who had worked on Notre Dame, Paris, and St. Denis, but St. Chapelle may have been the work of Robert de Luzarches or Thomas de Cormont.The building in fact houses two chapels. The lower, entered from the courtyard, was dedicated to the Virgin Mary and was for the use of servants of the royal household. It is relatively low its vaults are 22 feet (6.6 meters) high and rather dimly lit. Two small spiral staircases within the walls connect it to the upper chapel, for which it may have been designed as a foil; certainly, there is a breathtaking contrast in the quality of the respective spaces. The official access to the upper chapel, which was dedicated to the Holy Crown and the Holy Cross and reserved for the use of the sovereign, was by a gallery directly linking it with the royal apartments. Entering through a sculpture-enriched double portal, the visitor is greeted by an explosion of color and light. Fifteen lofty stained-glass windows, rising 65 feet (20 meters) from just above floor level to the gilded arches of the vaults, fill the entire area between the buttresses in total, 6,600 square feet (620 square meters) to create a space that has been described as Gothic architecture at its most daring and successful