The chapel is now operated as a museum by the French Centre of National Monuments, along with the nearby Conciergerie, the other remaining vestige of the original palace.

[4] In addition to serving as a place of worship, the Sainte-Chapelle played an important role in the political and cultural ambitions of King Louis and his successors.

[5][6] With the imperial throne at Constantinople occupied by a mere Count of Flanders and with the Holy Roman Empire in uneasy disarray, Louis' artistic and architectural patronage helped to position him as the central monarch of western Christendom, the Sainte-Chapelle fitting into a long tradition of prestigious palace chapels.

For the final stage of their journey they were carried by Louis IX himself, barefoot and dressed as a penitent, a scene depicted in the Relics of the Passion window on the south side of the chapel.

The Parisian scholastic Jean de Jandun praised the building as one of Paris' most beautiful structures in his "Tractatus de laudibus Parisius" (1323), citing: that most beautiful of chapels, the chapel of the king, most decently situated within the walls of the king's house, enjoys a complete and indissoluble structure of the most solid stone.

[18] The royal chapel is a prime example of the phase of Gothic architectural style called "Rayonnant", marked by its sense of weightlessness and strong vertical emphasis.

The chapel exterior shows many of the typical characteristics of Rayonnant architecture—deep buttresses surmounted by pinnacles, crocketted gables around the roof-line and vast windows subdivided by bar tracery.

Despite its decoration, the exterior is relatively simple and austere, devoid of flying buttresses or major sculpture and giving little hint of the richness within.

a major influence on its overall design may have come from contemporary metalwork, particularly the precious shrines and reliquaries made by Mosan goldsmiths.

Metal elements such as iron rods or chains, able to support tension, were used to replace the flying buttresses of previous structures.

The west front is composed of a porch two levels high, beneath a flamboyant Gothic rose window installed in the upper chapel in the 15th century.

At the top is a pointed arch an oculus window, and a balustrade around the bottom of the roof, decorated with interlaced fleur-de-lys emblems placed by Charles V of France.

The appearance of the first is unknown, but the second, built in 1383 under Charles V, is pictured in an illustration of the Tres Riches Heures du Duc de Berry.

[24] The lower chapel is only 6.6 meters (22 ft) high, with a six-meter wide central vessel and two narrow side aisles.

This was a clever illusion created by the master builder; each vertical support of the windows is composed of seven slender columns, which disguise their full thickness.

In addition, the walls and windows are braced on the exterior by two belts of iron chain, one at the mid-level of the bays and the other at the top of the lancets; these are hidden behind the bars holding the stained glass.

[26] There are two small alcoves set into the walls on the third traverse of the chapel, with archivolts or arches richly decorated above with painting and sculpture of angels.

The three windows of the eastern apse illustrate the New Testament, featuring scenes of The Passion (centre) with the Infancy of Christ (left) and the Life of John the Evangelist (right).

The next ten windows of the nave follow clockwise with scenes from Exodus, Joseph, Numbers/Leviticus, Joshua/Deuteronomy, Judges, (moving to the south wall) Jeremiah/Tobias, Judith/Job, Esther, David and the Book of Kings.

The final window, occupying the westernmost bay of the south wall brings this narrative of sacral kingship right up to date with a series of scenes showing the rediscovery of Christ's relics, the miracles they performed, and their relocation to Paris in the hands of King Louis himself.

One of the major works he recreated was the tympanum over the portal of the upper chapel, with a figure of Christ giving a blessing, with the Virgin Mary and John the Baptist alongside him.

[26] Sculpted Biblical scenes from the Old Testament fill the panels on lower walls, including the Creation and Noah's ark.

The arches of the tribune in the apse at the east end, where the case of sacred relics was placed, is ornamented with the original polychrome angels from the 13th century.

They systematically repainted the forty-four 13th-century quadrilobe medallions on the stone arches of the soubassements, which depicted the martyrdom of saints presented against a gilded background.

In 1983 the Service of Historic Monuments cleaned four of the medallions which had not been restored, and un-restored two which had been repainted, to study the original traces of paint from before 1845.

[33] The principal relics for which the chapel was built were the crown of thorns, believed to have been worn by Christ during his Passion, and a small piece of the cross on which he was crucified.

Two years later, he made an additional purchase from Baudouin of a piece of the true cross and other relics related to the Passion, which were brought to Paris in September 1241.

Thereafter, on each Holy Friday, the day of the Crucifixion, he conducted a solemn ceremony at Sainte-Chapelle, in which the relic was brought out and displayed to the faithful.

[37] For the patrons, such chapels served not only as public expressions of personal piety but also as valuable diplomatic tools, encouraging important visitors to come and venerate their relics and showing their connection to the French crown.

Notable Saintes-Chapelles in France include: As the status of Saint Louis grew among Europe's aristocracy, the influence of his famous chapel also extended beyond France, with important copies at Karlštejn Castle near Prague (c. 1360), the Hofburgkapelle in Vienna (consecrated 1449), Collegiate Church of the Holy Cross and St. Bartholomew, Wrocław (c. 1350) and Exeter College, Oxford (1860).