Sainte-Chapelle

Sainte-Chapelle was built by Louis IX (later Saint Louis) between 1242 and 1248 to house the Crown of Thorns that he had bought — at colossal expense — from Baldwin II of Constantinople. The relic itself is now at Notre-Dame (rescued from the 2019 fire) but the chapel remains, and it's the greatest surviving example of high gothic stained glass in the world.

The building has two levels. The lower chapel (7 m ceiling, painted vaults, columns clustered like palm fronds) was for servants and palace staff. The upper chapel — reached by a narrow spiral staircase — was reserved for the king, his court, and the relic. It's essentially a jewel box: 15 stained-glass windows, each 15 m tall, wrap around the walls with almost no stone between them, telling the biblical story from Genesis through the Passion in over 1,100 individual scenes. Two-thirds of the glass is original 13th-century work; the rest was carefully restored in the 19th century.

The trick to appreciating Sainte-Chapelle: come on a sunny day and stand in the middle of the upper chapel with your back to the entrance so the light streams over you. The blue and red panels do something to the interior air that photos genuinely cannot capture. Bring a small mirror if you want to see the details of the upper windows without craning your neck.

The chapel is inside the Palais de la Cité (the Conciergerie next door was the medieval royal palace, later a Revolution-era prison where Marie Antoinette was held). Combined ticket with the Conciergerie saves €5. Free first Sunday of the month, Nov–Mar only.