The Outlaws of Mars
After walking for a distance of about a mile he reached the edge of the garden, bounded by a wall about fifty feet in height, which stretched in a gradual curve to the right and left, as far as he could see. It was constructed from immense blocks of translucent, amber-colored material, fitted together so cleverly that the seams were all but invisible. At regular intervals, curving stairways led up to the top of the wall, and he made his way to the nearest one.
A short climb brought him to the top of the wall, which was more than a hundred feet thick. He walked across it and peered over the edge, then drew back dizzily. He was looking down on the busy streets of an immense city, so far belo