While the tube world unfolded all around them.

CHAPTER 42

It took two hours of descent before the transport compartment finally plunged down into the thicker clouds – although by now the blueness of the high air was visible beyond the walls.

Two hours: it was that fact alone, that this evidently high-speed transport had taken a whole two hours to cross a radius of one hub of this tremendous cylinder, that drove home to Mardina the sheer scale of the structure she was entering. It was already hundreds of miles back to the port where she had entered this habitat; it would not be rapid to travel anywhere in this great volume. At least now her weight felt comfortingly normal, even though the descent was not finished yet.

And when they passed through the high cloud layer, abruptly Mardina found herself looking down on mountains. Mountains that lapped up against the hub wall like a wave of rock breaking against the steel, mountains with ice clinging to their upper peaks and slopes, and glaciers spilling down their flanks.

The rail diverged from the wall now, though the transport box tipped up to stay vertical, and suddenly Mardina found herself skimming down an icebound slope of rock and frost-shattered scree. The landscape itself, at the foot of these mountains, was still far below.

‘This feels almost normal,’ she said.

Ruminavi grunted. ‘Until you remember there is a big band of these mountains all the way around the base of the hub wall.’

The ColU said, ‘Yes, of course – a mountain chain over a thousand miles long, like the mountains of Valhalla Inferior: South America, where the ancestors of these Incas arose. Folded up into a band!’

‘And all fake,’ Ruminavi said, grinning, trying to provoke a reaction – to awe them, Mardina realised. ‘Hollow! Built by engineers, shaped by artists! And inside the mountains there are big engines that circulate air and water and even stone, gravel and sand from the ocean.’

Mardina asked, ‘What ocean? Never mind.’

‘But look out at the spectacle …’

Abruptly the transport descended beneath the snow line, and now sped over bare rock. The view was giddy, with green-clad precipices falling away to the valleys of turbulent rivers below and those towering ice-clad peaks above, clawing at the metal face of the hub. Spectacular bridges spanned some of the gorges. And looking out now Mardina could see that some of the mountain’s face had been levelled into terraces, where people toiled; there were huts, fields, smoke rising from fires into the thin air. These were the first inhabitants of the cylinder they had seen since the hub.

‘Potato farmers,’ the ColU said. ‘Just as in the Andes in the time of the Incas. Our Incas. There they farmed all the way up to the snow line.’

Ruminavi frowned at the unfamiliar names. But he said, ‘Just as in the old country, we built mountains here as residences for our gods. The country is littered with shrines.’

‘Yes, the Incas came from the high lands,’ Mardina said. ‘I remember that from my own history, of what the Xin and the Romans found when they fought over Valhalla Inferior. There had been a mighty empire spanning the continent, but armed only with bronze swords and armour of leather …’

‘Just as the Europeans of my UN-China Culture discovered,’ the ColU said. ‘And destroyed. Here, however, the Incas evidently prospered. They overthrew Rome, they went out into space, and they brought their culture with them – indeed, they recreated it. Andean mountains, built of lunar rock perhaps.

‘Inguill called this habitat Yupanquisuyu, which means the Country of Yupanqui. And Cusi Yupanqui, at least in my culture’s timeline, was the man who truly established the Inca empire. He conquered vast swathes of territory, and established the empire’s legal, military and social structures. Yupanqui was their Alexander the Great, and it is as if this vast habitat is called “Alexandria”. So Yupanqui must have lived here too, in this reality; the histories must have been roughly consistent until that point – though, evidently, Rome survived to be defeated. I need to see the quipus, you know.’

‘The what?’

‘The frame of strings that quipucamayoc Inguill carried. That was, and evidently still is, the way the Incas kept their records. Somewhere in this artefact there must be a library, banks of knotted strings telling the story of this empire all the way back to Yupanqui himself. If only I could see it …’

Quintus Fabius had been listening. He said drily, ‘I’ll see what can be arranged, Collius. In the meantime it seems to me that this box of glass is slowing.’

In the last moments the transport entered another, lower bank of cloud that blanketed a green-tinged landscape.

Instructed by Ruminavi, the passengers picked up their gear and lined up by a side door. The axis warriors from the hub, fragile-looking in gravity, remained carefully strapped into their couches, but they kept the blunt muzzles of their ugly-looking weapons trained on the Romans. Meanwhile, waiting outside the door was another squad of soldiers to take over their supervision, heftier-looking types, their clothing gaudy, their dark faces stern and suspicious.

Mardina could see it would be just a short walk to the next transport, which was a kind of carriage on rails, one of a series, pulled by a heavy engine at the front. The rails of the track swept down the flank of the mountain.

‘Ah,’ the ColU said as he was carried out by Chu, ‘another railway system. A universal, it seems, across the timelines, common to all engineering cultures. Quintus, please ask Ruminavi what powers it – what is the motive force behind the engine?’

It took some moments of interrogation before the answer was extracted from the apu, and at that Quintus had to flatter him to make him brag about the mighty achievements of the Incas. The train, which he called a caravan, ran on the capac nans, the roads of the gods, which spanned this habitat from end to end. Ruminavi said the engine, which had a name something like ‘llama’, was powered by a warak’a, derived from an old Quechua word for ‘sling’ – and which turned out to be the Inca term for a kernel …

But Mardina, as she stepped out of the carriage, stopped paying attention to mere words. This steep mountainside was choked with green and swathed in mist, the moisture dripping from the crowding vegetation. The air was damp and fresh – but thin, hard to breathe, and she had a sense of altitude. Above her head, patchy clouds obscured her view of the higher mountains, which lifted islands of green into the air, like offerings. And beside the path that led to the railway, flowers bloomed in thick clusters with vivid colours, yellow, orange and purple, and tiny birds worked the flowers, flashes of brilliant blue.

The apu was watching her. He seemed to be admiring her show of interest, at least in comparison to the soldiers who stamped along the trail, already complaining about the state of their feet in a full gravity. ‘Cloud forest,’ he told her, a term that took some translating by the ColU.

‘And I suppose there’s a big band of this too all around the rim of the world.’

‘That’s how it’s designed. Come. It gets even prettier further down. All of this in a box in space.’ But he smiled at her a little too intensely, as if drinking in every detail of her face, her skin.

Mardina drew away and walked back to her group.

Once aboard the train they had to wait a full hour before it was ready to pull away.

There were many coaches bearing passengers, but the legionaries were herded into rougher carts evidently intended for freight. The Romans grumbled as they settled down, complained about the thinness of the air, the food grudgingly supplied by Inca troops – fruit, meat, water – supplemented by biscuits and other rations they’d brought in their packs from the Malleus. And, as soldiers always did whenever they got the chance, they tried to sleep.