In the middle of the story, when John crosses the river in a handmade raft to the "place of the gods", he beings to describe what he sees there.

From the text:

I saw both banks of the river—I saw that once there had been god-roads across it, though now they were broken and fallen like broken vines. Very great they were, and wonderful and broken—broken in the time of the Great Burning when the fire fell out of the sky.