The cliff against which they had buried the _Ra-Twelve_ was the loftiest section of an almost unbroken chain of mountains, surrounding the roughly circular hundred-mile plain, which was littered with beds of boulders and sand-hills, like a moon crater. What Peer had referred to as the "Mound" lay approximately at the center of the plain. It turned out, next morning, to be a heavily weathered, dome-shaped structure half a mile high and five miles across, which gave the impression that all but the top tenth of a giant's skull had been buried in the sand, dented here and there with massive hammers, and sprinkled thickly with rock dust. It was obviously an artifact--constructed with hundred-foot bricks! As the _Asteroid_ drifted down closer to it, Channok became interested. "Who built it?" he asked. Peer shrugged. She didn't know. "Santis spent a few hours jetting around the edges of it once," she said. "But he wouldn't tell us much; and, afterwards, he wouldn't let us get nearer than a mile to it. He didn't go back himself, either--said it was dangerous to get too close!" It didn't look dangerous. But fifty thousand years ago, it might have been a fortress of some sort. "You oughtn't to be flying so low over it, even!" Peer said warningly. "Right in the middle on top is where it's the most dangerous, Santis said!" Channok didn't argue the matter--they had to get Santis' special cargo cached and off their hands first, anyway. He lifted the _Asteroid_ a mile or so and then brought her down a couple of miles beyond the Mound, at the point Peer had designated. They got out of the ship and gazed about the broken, rocky plain. The red light of the Nameless Sun was spilling across it in what passed for morning on this world. In it, the black mountain chains rearing about the horizon and the craggy waves of flat land had the general effect of a bomb-shattered and slowly burning city. Far off to their left, he could see the upper half of the towering precipice which marked the _Ra-Twelve's_ resting-place. "How long a time did you say you spent here?" he asked. Peer reflected. "About two Terra-months, I guess. I'm not sure, though. That was a long time ago. My youngest brother Dobby wasn't born yet." He shook his head. "What a spot for a nice family picnic!" "It wasn't a picnic," Peer said. "But my kid brother Wilf and I had a lot of fun anyway, just running around and teasing the ghouls. I guess you don't notice so much what a place looks like when you're little." "Teasing the what?" "Ghouls," said Peer carelessly. He looked at her suspiciously; but she seemed to be studying the nearby terrain for a good spot to start digging. "And what were Santis and your mother doing?" he inquired. "They were looking for some sort of mineral deposit on Old Nameless; I forget just what. How about that spot--just under that little overhang? It looks like good, solid top-rock." * * * * *