V

Finally, though, we did encounter exactly the opening we wished; an archway about six feet wide and ten feet high, marking the former end of an aerial bridge which had spanned an alley about five feet above the present level of glaciation. These archways, of course, were flush with upper-story floors, and in this case one of the floors still existed.

The building thus accessible was a series of rectangular terraces on our left facing westward. That across the alley, where the other archway yawned, was a decrepit cylinder with no windows and with a curious bulge about ten feet above the aperture. It was totally dark inside, and the archway seemed to open on a well of illimitable emptiness.

Heaped debris made the entrance to the vast left-hand building doubly easy, yet for a moment we hesitated before taking advantage of the long-wished chance. For though we had penetrated into this tangle of archaic mystery, it required fresh resolution to carry us actually inside a complete and surviving building of a fabulous elder world whose nature was becoming more and more hideously plain to us.

In the end, however, we made the plunge, and scrambled up over the rubble into the gaping embrasure. The floor beyond was of great slate slabs, and seemed to form the outlet of a long, high corridor with sculptured walls.

Observing the many inner archways which led off from it, and realizing the probable complexity of the nest of apartments within, we decided that we must begin our system of hare-and-hound trail blazing. Hitherto our compasses, together with frequent glimpses of the vast mountain range between the towers in our rear, had been enough to prevent our losing our way; but from now on, the artificial substitute would be necessary.