Thanks largely to the efficiency of the flying buttress and six-part rib vaults, All of the major High Gothic cathedrals except Bourges used the three-level elevation, eliminating the tribunes and keeping the ground floor grand gallery, the triforium, and the clerestory, or high windows.
The upper windows in particular grew in size to cover almost all of the upper walls.
The arcades also grew in height, occupying half the wall, so the triforium was just a narrow band.
The upper windows were often made of translucent grisaille glass, which allowed more light than colored stained glass.

Bourges Cathedral, begun in 1195, was more complicated.
It did not seek a visual unification of the nave, but rather greater diversity.
The nave was taller than the side aisles, but each had three levels, which did not match.
Thus the naves and aisles had separate galleries, triforia and clerestories of different heights, or five different levels in all.
This same system was adapted at Le Mans Cathedral and Coutances Cathedral in France and Toledo Cathedral and Burgos Cathedral in Spain.
Thanks largely to the efficiency of the flying buttress and six-part rib vaults, All of the major High Gothic cathedrals except Bourges used the three-level elevation, eliminating the tribunes and keeping the ground floor grand gallery, the triforium, and the clerestory, or high windows. The upper windows in particular grew in size to cover almost all of the upper walls. The arcades also grew in height, occupying half the wall, so the triforium was just a narrow band. The upper windows were often made of translucent grisaille glass, which allowed more light than colored stained glass.
Bourges Cathedral, begun in 1195, was more complicated. It did not seek a visual unification of the nave, but rather greater diversity. The nave was taller than the side aisles, but each had three levels, which did not match. Thus the naves and aisles had separate galleries, triforia and clerestories of different heights, or five different levels in all. This same system was adapted at Le Mans Cathedral and Coutances Cathedral in France and Toledo Cathedral and Burgos Cathedral in Spain.
High Gothic