The "flamboyant" style was characterised by the multiplication of the ribs of the vaults, with new purely decorative ribs, called tiercons and liernes, and additional diagonal ribs. One common ornament of "flamboyant" in France is the "arc-en-accolade", an arch over a window topped by a pinnacle, which was itself topped with fleuron, and flanked by other pinnacles. Examples of French "flamboyant" building include the west façade of Rouen Cathedral, and especially the façades of Sainte-Chapelle de Vincennes (1370s) and choir Mont-Saint-Michel's abbey church (1448).