 The elevations of earlier Gothic cathedrals usually had four levels to give them solidity; an arcade of massive columns on the ground floor, supporting a wide arched tribune gallery or tribune, below a narrower arcade triforium; then, under the roof, the higher and thinner walls, or clerestory, where the windows were.Thanks to the buttresses, the architects of Chartres could eliminate the gallery entirely, make the triforium very narrow, and have much more room for windows above.Chartres was not the first cathedral to use this innovation, but it used it much more consistently and effectively throughout.