One more church.  This is the magical Sainte Chapelle completed in 1248.  It was built to house the crown of thorns purchased at about four times the value of the church from the wily Baudouin II, Emperor of Constantinople. Sainte Chapelle is about 2 blocks from Notre Dame And is inside the Palais de Justice. The altar is on the first floor, so you'd better be quiet. The thing about Sainte Chapelle is the amazing stained glass on the second floor.  The roof and towers seem to be held up by the stained glass windows alone. The stained glass tells the entire story of the Bible, from Genesis to the rose window containing the book of Revelations The Palais de Justice was built around Sainte Chapelle for protection.