Built by King Louis IX to house his newly purchased holy relics (e.g. the Crown of Thorns), the Sainte-Chapelle was completed in 1248. The small chapel is one of the finest examples of the High Gothic style of architecture. The immense stained glass windows that were a remarkable achievement for their time have never failed to impress during the intervening 750 years and the beautiful rosette is an unforgettable marvel. A must-see for any admirer of art.