Symat was fourteen years old, however, and that was exactly how old the world was to him. And he was unhappy for much more immediate reasons than man’s cosmic destiny. He stumbled on, alone.

It was hours since he had stormed out of his parents’ home, though the changeless day made it hard to track the time. Nobody knew where he was. He had instructed the Mist, the ubiquitous artificial mind of Mars, not to follow him. But the journey had been harder than he had expected, and he was already growing hungry and thirsty.

It might have been easier if his journey had a destination, a fixed end. But he wasn’t heading anywhere as much as escaping. He wanted to show his parents he was serious, that his refusal to join the great exodus from reality through the transfer booths wasn’t just some fit of pique. Well, he’d done that. But his flight had a beginning but no end.

Trying to take his mind off his tiredness, he stared into the sliver of sun on the horizon. Sol was so big and red it didn’t hurt his eyes, even when he gazed right into it. The sun never moved, of course, save for its slow rise as you walked towards it.

The sky of Mars had changed, across a million years. Symat knew that Mars’s sky had once had three morning stars, the inner planets. But Venus and Mercury had long been eaten up by the sun’s swelling, Earth wafted away, and Mars was the closest of the sun’s remaining children.

And that sun never shifted in the sky. These days Mars kept one face turned constantly towards the sun, and one face away from it: one Dayside, one Nightside, and a band of twilight between where the last people lived.

Something briefly eclipsed the sun. He stopped, blinking; his eyes were dry and sore. He saw that he had passed through the shadow of a spire.

He walked on.

Soon he entered a city. The buildings were tall and full of sunlight, and bridges fine as spider web spanned the canal water. But there were no people walking over those bridges, no flitters skimming around the spires, and red dust lay scattered over the streets. It was like walking through a museum, solemn and silent.

One building bulged above his head, a ball of smooth, fossil-free Martian sandstone skewered on a spire of diamond. Clinging to the bank of the canal Symat gave it a wide berth: even after all this time human instincts remained shaped by the heavier gravity of Earth, where such an imbalanced structure would have been impossible.

Time had made its mark. Right in the heart of the city one slender bridge had collapsed. He could see its fallen stones in the water, a line of white under the surface.