'What's that?' she asked, pointing towards what appeared to be a nebulous cloud of dust and reflective particles just over the horizon.

'That is the remains of an active construction site,' said Rho-mu 31. 'The latest ships to be built here have but recently departed.'

'Where have they gone?' asked Dalia, eager to learn what far-off place the new vessels were bound for.

'They were commissioned for Battlefleet Solar,' explained Rho-mu 31, 'but the Warmaster issued a new tasking order to have them despatched to take part in the Istvaan campaign.'

Dalia heard the note of disapproval in Rho-mu 31's voice, as though it were the greatest sin imaginable to change procedure and alter previously issued orders.

'Look, there is the fleet they were to join,' said Rho-mu 31, indicating berths high above them, and Dalia's mouth dropped open as the mighty warships of Battlefleet Solar came into view.

Distance rendered the fleet small, but to even recognise them and identify individual vessels from so far told Dalia that they were craft of unimaginable scale. From here they were sleek darts with sloping angular prows like ploughs and long, gothic bodies like great palaces hurled into the heavens and wrought into the forms of starships.

The ships were soon lost to sight as creeping fire slid along the length of the starship, the heat of passing through the atmosphere of Mars rippling along the shielded hull of the vessel. Dalia felt a steadying hand on her shoulder, a heavy, metallic hand that gripped her tightly as the starship continued its descent.

Flames and heat distortion soon obscured the view, but within the space of a few minutes it faded, and Dalia saw the surface of Mars in all its glory.

Vast cities of steel, larger and more magnificent than any of the hives of Terra, reared up from the surface, gargantuan behemoths that vomited fire and smoke into the sky. It was called the red planet, but precious little remained of the surface that could be identified as that hue. Mountains had been clad in metal and light, and cities and districts perched on the peaks and plateaux of the world named for a long forsaken god of war.

Glittering streams of light twisted and snaked through the few areas of cratered wilderness between the unimaginably vast conurbations, transit routes and mag-lev lines, and towering pyramids of glass and steel reared up like the tombs of forgotten kings.

'I've read about Mars, but I never thought to see it,' breathed Dalia. To see so many wondrous things in so short a time was nothing less than overwhelming.

'The Martian priesthood does not encourage visitors,' said Rho-mu 31. 'They believe the soil of Mars to be sacred.'

'Isn't the idea of things being sacred, well… not allowed any more?'

'In a manner of speaking, yes,' agreed Rho-mu 31. 'The Emperor advances the credo that belief in gods is a falsehood, but a condition of the Treaty of Olympus was that he swore not to interfere with our structures and society when Mars and Terra were joined.'

'So the Mechanicum believes in a god?'

'That is a question with no easy answer, Dalia Cythera. I do not believe in faith, but ask no more, for we are coming in to land and you will need to hold on tightly.'

Dalia nodded as the ship banked sharply, and she watched the world below tilt crazily as the pilot brought them around a shining pyramid bathed in light and topped with a great carving of an eye.

'The Temple of All Knowledge,' said Rho-mu 31, anticipating her question.

Dalia felt her stomach lurch as the ship dropped suddenly and a thick curtain of yellow smog obscured the view outside.

They flew through the smog for several hours until, as suddenly as it had appeared, it vanished, and Dalia cried out in terror as she saw that they were heading straight into the glassy black flanks of a towering mountain.

Once again, Dalia's stomach lurched as the craft's altitude altered rapidly, climbing at a sickeningly steep angle as the black cliff-face drew closer with terrifying rapidity. Sulphurous fumes wreathed the top of the mountain and the craft plunged into them. Dalia closed her eyes, expecting any moment to have her life ended as they smashed into the immovable mass of rock.

At last she opened her eyes when the feared impact didn't come and peered breathlessly through the transparent panel in the side of the craft. A sea of glowing red lava heaved and swelled beneath her, the volcanic heart of the planet bubbling up within the giant mountain.

Her view of the volcano's caldera shimmered and danced in the incredible heat radiating from the lava, and though she was insulated from the unimaginable temperatures, Dalia felt uncomfortably warm just looking at the molten rock.

'Arsia Mons,' said Rho-mu 31. 'A dead volcano brought back to life to serve the Mechanicum.'

'It's incredible,' breathed Dalia, looking over to the far side of the caldera, where a huge, industrial city-structure fashioned from what looked like blackened steel and stone rose from the lava like the broadside of a submerged starship. Enormous gates steamed in the lava, and mighty pistons of gleaming ceramite hissed and groaned as they rose and fell. Billowing clouds of superheated steam roared and vaporised like the breath of a host of great dragons, and Dalia saw that they were gaining height to fly over the bizarre structure.

Closer now, she could truly appreciate its enormous size and complexity, a precise series of sluices, overflow channels and pressure gates to keep the lava in motion and circulating through the system that fed the incredible sight on the far side of the volcano.

Guided down the flanks of the mountain in enormous chasms a hundred metres wide, the lava from the volcano fed a vast artificially constructed lagoon, an inland sea of glowing, hissing, bubbling molten rock.

Built upon this sea was the Magma City, and what a city it was…

Dalia's breath was snatched from her throat as she saw the mighty forge, surely the domain of Rho-mu 31's master, Adept Koriel Zeth.

All across the bubbling, flame-wracked surface of the lava, blackened cylinder towers soared from the magma beside giant structures in the shapes of flat-topped pyramids that belched fire and steam. Twisting roadways, boulevards, open squares, wide platforms and entire industrial complexes sat upon the raging heat of the lava in defiance of the awesome caged power of the planet's molten fire.

A golden route traced a path towards a mighty structure of silver in the centre of the colossal metropolis, but it was quickly lost to sight as the craft descended. Thick retaining walls of dark stone surrounded the lagoon, such that it resembled a lava-filled crater, and a colossal plain of sub-hives, hab-zones, landing fields, runways, control towers and a vast container port filled the horizon behind it, abutting the cliff-like walls of the volcano.

Continents of steel-sided containers sprawled outwards from the Magma City, towering skyscrapers of materiel: weapons, ammunition and supplies manufactured in the factories of Mars for the Warmaster's armies of conquest.

Fleets of enormous vessels filled the skies over the port, rising and descending to the surface of Mars in a veritable procession of steel and retro-fire. Each one was destined for worlds far distant from the Solar system and as valuable to the Great Crusade as any warrior or battleship.

A forest of lifter-cranes swung and groaned over the container port, their heavy, counterbalanced arms moving with leisurely speed in an intricate ballet as an army of servitors, loaders and container skiffs packed the holds of the enormous bulk conveyors with as much as could physically be contained.

Dalia held onto the stanchion as the ship banked, heading towards a landing platform within the city, a glowing cross of light sitting on a boom of metal that jutted out into the lava. The view through the photomalleable steel rippled in the heat, and Dalia found herself becoming nauseous with the disorientation.