Man had been in space for only three hundred years. Whatever had built these had been in space for thousands of years. Which ought to give _them_, thought Steffens uncomfortably, one hell of a good head-start. * * * * * While the excav crew worked steadily, turning up nothing, Steffens remained alone among the buildings. Ball came out to him, looked dryly at the walls. "Well," he said, "whoever they were, we haven't heard from them since." "No? How can you be sure?" Steffens grunted. "A space-borne race was roaming this part of the Galaxy while men were still pitching spears at each other, _that_ long ago. And this planet is only a parsec from Varius II, a civilization as old as Earth's. Did whoever built these get to Varius? Or did they get to Earth? How can you know?" He kicked at the sand distractedly. "And most important, where are they now? A race with several thousand years...." "Fifteen thousand," Ball said. When Steffens looked up, he added: "That's what the geology boys say. Fifteen thousand, at the least." Steffens turned to stare unhappily at the buildings. When he realized now how really old they were, a sudden thought struck him. "But why buildings? Why did they have to build in stone, to last? There's something wrong with that. They shouldn't have had a need to build, unless they were castaways. And castaways would have left _something_ behind. The only reason they would need a camp would be--" "If the ship left and some of them stayed." Steffens nodded. "But then the ship must have come back. Where did it go?" He ceased kicking at the sand and looked up into the blue-black midday sky. "We'll never know." "How about the other planets?" Ball asked. "The report was negative. Inner too hot, outer too heavy and cold. The third planet is the only one with a decent temperature range, but _it_ has a CO_{2} atmosphere." "How about moons?" Steffens shrugged. "We could try them and find out." * * * * * The third planet was a blank, gleaming ball until they were in close, and then the blankness resolved into folds and piling clouds and dimly, in places, the surface showed through. The ship went down through the clouds, falling the last few miles on her brakers. They came into the misty gas below, leveled off and moved along the edge of the twilight zone. The moons of this solar system had yielded nothing. The third planet, a hot, heavy world which had no free oxygen and from which the monitors had detected nothing, was all that was left. Steffens expected nothing, but he had to try. At a height of several miles, the ship moved up the zone, scanning, moving in the familiar slow spiral of the Mapping Command. Faint dark outlines of bare rocks and hills moved by below. Steffens turned the screen to full magnification and watched silently. After a while he saw a city.