portal. The center portal also contains depictions of New York City skyscrapers being destroyed in an apocalypse. The center, northernmost, and southernmost portals are set within large, gabled structures with several archivolts, or arched moldings, surrounding each portal under the gables; porches overhang the portals above the gables. The other two portals are located under simple rectangular canopy structures, located underneath grisaille windows looking into the nave. Lights salvaged from the former Pennsylvania Station illuminate the steps in front of the portals. Above the center portal, between the towers, is a rose window installed by stained glass artist Charles Connick and constructed out of 10,000 pieces of glass. With a diameter of , the rose window is the largest rose window in the U.S. Flanking the rose window on either side are two grisaille windows, each with two lancet windows under a smaller rose. The seven archangels are depicted in the north grisaille, while the seven churches of Asia are depicted in the south grisaille. Connick had designed the grisailles as well. On the gable above the large rose window, there are lancets as well as a medallion in the middle. The two pairs of great west doors on the western elevation, set beneath the elaborate center portal, were designed between 1927 and 1931 by the designer Henry Wilson. The bronze doors include a sequence of 60 relief panels, which presents scenes from the Old and New Testaments and the Apocalypse. The doors open three times per year: Easter; St. Francis's feast day in October; and the "blessing of the bicycles" in the spring. They comprise one of four bronze-door commissions designed by Wilson before his death. St. John's great west doors were the last of the four commissions, each pair measuring some . The remaining doors on the western elevation are composed of Burmese teak with wrought iron decoration. Nave The nave was designed by Cram, though the final plan is slightly modified from the original. It is oriented from west to east, measuring long by wide. The ceiling is above ground level, but the ridge of the roof is high. These dimensions are about the same as in the original plans, which called for floor dimensions of . a roof, and a ceiling. On the northern and southern elevations, there are four vertical "double bays", each with two columns of windows. Large arched buttresses, with two piers each,