the Rayonnant period, the west façades and portals were lavishly decorated with pointed gables, the points of which often included small circular windows, plus an array of sculptured pinnacles and fleurons, as illustrated in the ornate decoration of the Basilica of St Urbain, Troyes (1262–1389). Besides serving as a decoration, the pinnacles had a structural function; they added weight to the buttresses, giving greater support to the walls. Elevations In early Gothic cathedrals, the walls of the nave were about equally divided between the arcades on the ground floor, the Tribune, an arcaded passage above, which buttressed the nave; above that the narrow arcaded Triforium which was a passageway which further reinforced the walls; and the clerestory on the top, just below the vaults, which usually had small windows. This changed dramatically in the Rayonnant period. Thanks to the more efficient flying buttress and quadripartite rib vaults, the walls could be higher and thinner, with more space for windows. The arcade became higher and higher, with much larger openings. The tribune, no longer needed for support, disappeared entirely. The intermediate triforium nearly disappeared, or was itself filled with windows. Most impressive was the change to the top level, the clerestory, supported by longer buttresses; the upper walls were filled with larger and larger windows, until the walls at that level nearly disappeared. The final architectural innovation that emerged as part of the Rayonnant style in France was the use of glazed triforia. Traditionally, the triforium of an Early or High Gothic cathedral was a dark horizontal band, usually housing a narrow passageway, that separated the top of the arcade from the clerestory. Although it made the interior darker, it was a necessary feature to accommodate the sloping lean-to roofs over the side aisles and chapels. The Rayonnant solution to this, as employed to brilliant effect in the 1230s nave of the Abbey Church of St Denis, was to use double-pitched roofs over the aisles, with hidden gutters to drain off the rainwater. This meant the outer wall of the triforioum passage could now be glazed, and the inner wall reduced to slender bar tracery. Architects also began to emphasise the linkage between triforium and clerestory by extending the central mullions from the windows of the latter in a continuous moulding running from the top of the windows down through the blind tracery of the triforium to the string course at