Yet most of the city, supposedly built before the evolution of mankind on Earth, appeared untouched by the ages. The dry weather could account in part for that; there were no storms here, and rain had not fallen since Muller’s arrival. But wind and windblown sand could carve walls and pavements over a million years, and there was no sign of such carving here. Nor had sand accumulated in the open streets of the city. Muller knew why. Hidden pumps collected all debris, keeping everything spotless. He had gathered handfuls of soil from the garden plots, scattering little trails here and there. Within minutes the driblets of soil had begun to slither across the polished pavement, vanishing into slots that opened briefly and closed again at the intersection of buildings and ground.

Evidently beneath the city lay a network of inconceivable machinery—imperishable caretaker devices that guarded the city against the tooth of time. Muller had not been able to reach that network, though. He lacked the equipment for breaching the pavement; it seemed invulnerable at all points. With improvised tools he had begun to dig in the garden areas, hoping to reach the sub-city that way, but though he had driven one pit more than a dozen feet and another even deeper he had come upon no signs of anything below but more soil. The hidden guardians had to be there, however: the instruments that operated the viewing tanks, swept the streets, repaired the masonry, and controlled the murderous traps that studded the outer zones of the labyrinth.

It was hard to imagine a race that could build a city of this sort —a city designed to last millions of years. It was harder still to imagine how they could have vanished. Assuming that the fossils found in the burial yards outside the walls were those of the builders—not necessarily a safe assumption—this city had been put together by burly humanoids a meter and a half tall, immensely thick through the chest and shoulders, with long cunning fingers, eight to the hand, and short double-jointed legs.

They were gone from the known worlds of the universe, and nothing like them had been found in any other system; perhaps they had withdrawn to some far galaxy yet unvisited by man. Or, possibly, they had been a nonspacegoing race that evolved and perished right here on Lemnos, leaving this city as their only monument...

Had they been invaded by beings for whom the maze posed no problems, and had they been slaughtered in their own sleek streets, and had the mechanical wardens swept away the bones? No way of knowing. They were gone. Muller, entering their city, had found it silent, desolate, as if it had never sheltered life; an automatic city, sterile, flawless. Only beasts occupied it. They had had a million years to find their way through the maze and take possession. Muller had counted some two dozen species of mammals in all sizes from rat-equivalent to elephant-equivalent. There were grazers who munched on the city’s gardens, and hunters who fed on the herbivores, and the ecological balance seemed perfect. The city in the maze was like unto Isaiah’s Babylon: wild beasts of the desert shall lie there; and their houses shall be full of doleful creatures; and owls shall dwell there, and satyrs shall dance there.