From 1135, Abbot Suger decided to rebuild the old Carolingian church of Saint-Denis to display the relics of St. Denis in a new choir. He enlarged the Romanesque crypt, whose solid pillars provided support for the chevet, itself elevated. To bring light into the choir, Suger asked his architect to use the very recent technique of cross-ribbing, which allowed large windows to be opened in the walls. Master glassmakers created on site the basilica’s stained glass windows, which were unusually large for the time. They even developed a new blue – the blue of Saint-Denis – based on cobalt.