I was too low. I ascended perhaps another thousand feet. When I was again hanging stationary, I found beneath me a tremendous terraced building--a pyramid with its apex sliced off. To the north and south it connected with others of its kind; giant structures generally of pyramid shape, with streets running along their steplike terraces. Innumerable bridges connected these mammoth buildings, so that north and south, and for a few blocks east and west of the center, there were continuous aerial streets, in some places as many as ten or fifteen, one above the other. I turned to the window facing the north. There was now nothing but buildings as far as my line of vision extended; buildings like a ridge down the center, shading off to the lower areas of the east and west. There were trees and parks in spots on the top, but the original ground was covered. Some of the upper street levels--those alternate sections of terraces and bridges over courtyards whose ground was merely the rooftops of lower edifices--were laid with gleaming rails. And rearing itself above everything, a skeleton structure of monorails stretched north and south--eight or ten single rails paralleled at widths of some fifty feet, which I realized must be carrying some system of aerial railroad. This towering pile was indeed the backbone of the city, extending roughly north and south like a mountain range that forms the backbone of a continent. The lower areas adjacent--five hundred feet above the ground, perhaps--were for the most part buildings with broad, flat roofs. In New Jersey, on Long Island, and north of Manhattan as far as I could see, lesser cities had appeared, with occasional giants among buildings that were lower. The whole was now welded into one, for the rivers on each side of me were spanned by a bridge at almost every street; a network of bridges under which the water flowed almost unnoticed. My time-velocity was still accelerating. I saw now, increasingly, many things about the city that were shadowy--structures that were erected and stood no more than twenty or thirty years, perhaps, which to my vision now was only a moment. I became aware, not only below me, but even above me, of occasional vague aerial structures; skeletons that reared themselves up a few thousand feet and dissipated into nothing before I could form a conception of their real nature. There was, indeed, everywhere this shadowy aspect as to detail. Changes were taking place; things were being done even the effect of which was too fleeting for my vision to grasp.