But most wonderful of all the things that lay before us in that moment was the fact that nowhere about us could we see any sign of supporting pillars or piers for the giant roof that stretched far above us! For though we could gaze far away to the distant horizons of this great world, we could find no single support for that huge metal roof that apparently covered all the great planet, and whose weight must have been incalculable! And another feature of the giant roof puzzled us. It puzzled us to see the great openings in it like that down which we had come, great circular openings which we could see in it here and there at great distances from each other. Those openings were provided on their under-side with great sliding shutters for closing them tightly, yet all were open! Why should they be open, we silently asked ourselves, if the purpose of the roof was to retain Neptune's heat within that roof? For the existence of those great and unclosed openings in the roof must surely be defeating that purpose, for our outside-temperature dial recorded the same zero temperature as prevailed above the roof! Yet even these strange things could not wholly draw our interest and attention from the strange compartment-city beneath, as our space-flier sank toward it. We were within a few hundred feet of it, now, and as we dropped nearer, Marlin and Whitely and Randall staring eagerly down beside me, my hands were tense upon the switch-controls, ready to send our flier leaping instantly upward. For if the beings of the city beneath, whatever their nature, caught sight of us, we could expect nothing but instant attack. So that a tenseness held all of us as our great flier's faceted polyhedron dropped on through the pale light beneath the great roof toward the black-walled, checkerboard-like city that stretched across the surface of the great world beneath us. And now, as we sank lower, our eyes were making out ever more clearly the details of that amazing city. The rectangular black-walled compartments held, as we had half-realized from above, various strange-shaped mechanisms and objects which we could even now only vaguely discern. We could see clearly, though, that here and there across all the vast city's compartmented surface there stood giant metal globes, each a hundred feet in diameter and each occupying a square compartment of its own. There seemed hundreds of these great gleaming globes, scattered here and there in compartments across the city's surface as far as we could see, though their purpose was then quite incomprehensible to us. But as we sank lower still, ever more cautiously, it was not the globes or the compartments' contents that held our attention so much as the astounding, stupefying fact that now was thrust upon us--namely that in all the gigantic compartmented city, in all its strange great black-walled rectangular and roofless enclosures, _there moved no living being_!