sentences:  During the High Gothic period, with the development of the four-part rib vault and the flying buttress, the tribune was eliminated at Chartres and other new cathedrals, allowing taller windows and arcades.By the 15th century, at Rouen Cathedral, the triforium also disappeared, and the walls between the traverses were filled with high windows.Another innovative feature of the French Gothic cathedral was the design of the portal or entry, which by long Christian tradition faced west.