The narthex is the portion of the cathedral just inside the west front, beneath the tower. It is separated from the nave by two massive pillars, 8.5 by 5 meters, which support the tower above. The primary decorative element is the rose window, added between 1320 and 1340, and substantially restored since. Rays of yellow glass radiate outwards like a sun, surrounded mosaic-like pieces of green and blue and by small oculi with red floral designs. The tracery and decoration of the interior are very much like of that exterior, with blind galleries and delicate parallel vertical lines, like the strings of a harp. A pointed arch frames the window, and a row of blind arches at the lower level completes the decoration.