Sainte-Chapelle (săNt-shäpĕlˈ) [key], former chapel in Paris. Forming part of the buildings of the Palais de Justice (once the royal palace) on the Île-de-la-Cité, it was built by Pierre de Montreuil (1243–46) for Louis IX (St. Louis) to enshrine the Crown of Thorns and other sacred relics brought back from the Crusades. It was admirably restored in the 19th cent. by J. B. Lassus and Viollet-le-Duc. Now a museum, the Sainte-Chapelle is one of the finest examples of medieval art. It consists of two chapels, one above the other, and a spire. A winding staircase leads from the painted and gilded lower chapel to the porch of the upper chapel. The elegant proportions and airiness of the upper chapel, its 15 magnificent stained-glass windows, separated only by thin colonnettes and reaching nearly from floor to ceiling, and its vividly painted columns and panels combine to create the effect of a sheer blaze of color and light. The Sainte-Chapelle is a superb example of the Rayonnant style in Gothic architecture.