Crossing the space to be occupied by the West Front, we ascend temporary steps to the foundation of the Nave (figure 2 of plan). Superstructure not yet begun (June 15th, 1924). Here the visitor should pause and imagine himself entering the western limb of the Cathedral, 225 feet long, 132 feet wide, 175 feet high outside and 130 feet high inside, built in pure 13th century Gothic adapted to the requirements of the plan. The central aisle,[16]—as wide between the centers of piers as 112th street is between building lines—has two narrower aisles on each side. Instead of the closely-grown-up forest effect produced by the columns of many Gothic cathedrals, an air of openness and spaciousness, which distinguishes this Cathedral throughout, is given by the relatively small number of piers and columns and their ingenious disposition. In this arrangement the architect has made two notable departures from the ordinary Gothic type: One is the erection of the clerestory on the secondary line of columns (those nearest the side walls,) which modifies the exterior system of flying buttresses, and the other is the introduction of intermediate slender columns in the primary line of piers, resolving the Nave into a system of four squares or double bays instead of eight rectangular bays. As the primary ranges of piers and columns rise to the spring of the arches which support the roof of the Nave, instead of being shortened to support the clerestory, an effect of great spaciousness and lofty aspiration is produced; and this arrangement, together with the rhythmic alternation of great piers and relatively small clustered columns, allows a play of light and shade surpassing that of any mediaeval cathedral. Under the roofs of the north and south aisles runs the triforium gallery; and there are many beautiful details of ornament, including the tracery, panelling, capitals, niches, pinnacles and sculptures. A light and cheerful effect is produced by the illumination through 32 stained glass windows—eight in the aisle and eight in the clerestory on each side,—and the great Rose Window in the west end. While standing at the west end of the foundation, the visitor should survey the great area of floor space that lies before him; then, looking eastward 225 feet (the length of a city block and half the width of a street) imagine the present temporary west wall of the Crossing removed, and the view extended about 225 feet farther to the High Altar in the Sanctuary. He will then have an idea of the great vista of the completed church. [Illustration: ONE SIDE OF THE INTERIOR OF THE NAVE (Composite Photograph of Model. Figures of choristers show scale)]