Mars was indeed inhabited. This fact was borne home by the canals and the very evident artificial nature of their construction. They could see clearly through their telescopes that there was an intricate global network of pipelines, pumping stations, and irrigation viaducts from pole to pole. They also saw that at the intersections of the canals were dark sections crisscrossed with thin blobs of gray and black which proved under the telescopes to be clusters of buildings. There were cities on Mars, linked by the waterways. They saw no aircraft. They detected no railroad lines or roadways beyond the canalways themselves. The many regions of darker, better ground, intersected by the canals which no longer fulfilled their purposes, were covered with thick vegetation--forests of dying, wintery stalks. Only a flicker of dark green here and there showed where some faint irrigation still got through. They saw also that there were lines of white, which had not been visible before. Snow was gathering in low spots, and the planet was freezing up. The lines of solar distortion were strong, and they traced them to their point of concentration. The point was not some isolated spot far in a desert, away from Martian investigation. To the amazement of the men, the location of the Sun-tap station was actually within a Martian city! "Do you suppose," Lockhart queried the others, "that the Martians themselves are the builders of this setup--that this is their project--that they are the criminals and not the victims?" There was no answer. The evidence was apparent, but it made no sense. If the Martians had created this thing, it was destroying them. And yet, if they had not created it, why did they--so clearly a race that had attained a high level of engineering ability--tolerate its continual existence? As the ship descended, they saw the city emerge. It consisted of hundreds of gray mounds--buildings laid out in the form of neat hemispherical structures, like skyscraper igloos, with rows of circular windows. Each building was like the next, and they fitted together in a series of great circles, radiating outward from the meeting spot of the canals. The explorer crew waited at the ship's rocket launchers for an attack. The tail of the teardrop housed the built-in armament--the rocket tubes which could send forth destruction to an enemy. But though Haines sat with his finger on the launcher button, no aircraft rose to meet them from the city below. No guns barked at them. No panic started in the streets. They could see tiny dots of living beings moving about, but no sign of alarm, no evidence that they had been noticed. Even here, at the equator, there were streaks of white snow in the streets and rings of rime along the bases of the buildings. Directly below them lay the Sun-tap station. The lines converged here, and the rings of distortion could be seen in the atmosphere, causing the city to flicker as if from the presence of invisible waves.