The Saint-Denis Basilica stands on the site of a Gallo-Roman cemetery, the burial place of St. Denis, who was martyred around 250 A.D. In addition to the Carolingian crypt, which is a remnant of the abbey church consecrated in the presence of Charlemagne in 775, the basilica has two elements that are emblematic of the beginnings of gothic architecture. The oldest is the ‘chevet’ of Abbot Suger (built between 1140 and 1144) decorated with stained glass windows. Then in the 12th century, Louis IX had the transept enlarged to accommodate the royal tombs. The Saint-Denis Basilica remained the necropolis of the kings of France until the 19th century.