The Gothic style Sainte-Chapelle is a royal chapel on the Île de la Cité in central Paris. It was built in 1248 by King Louis IX (aka St. Louis) to house relics of Jesus purchased from the east. The relics included the alleged "crown of thorns", which has been housed in the Notre-Dame since 1806.
It is part of a cluster of buildings currently used as court houses. The building houses two chapels, a lower chapel and an upper chapel, which is famous for its 13th century stained glass windows. The restoration of the windows were completed in 2015.