Robert and Moraima found their fathers at the gate in the city walls. Ibn Hafsun the muwallad stood by with horses.

Sihtric was impatient, fretting. 'Where have you been? You do not keep the vizier of an emir waiting.'

'Ibn Tufayl will understand,' Moraima said, unconcerned.

Sihtric fumed, but his anxiety to be away got the better of him. They mounted their horses and rode out into the dust of the country.

They headed west, following a road that climbed away from the city by its river. Buildings trailed along this road, some grand residences; evidently it was a road often travelled by the wealthy. But many of the houses looked abandoned, their pretty patios overgrown.

They came to what Robert thought was another town, smaller than Cordoba but still extensive. They paused on a ridge, looking out over this place. Surrounded by a complicated double-wall system, it was largely ruined, buildings burned out, ponds and canals choked with weeds, the wild greenery taking back the gardens.

'This was no town,' Sihtric said. 'It was a palace. Its name is Madinat az-Zahra. Built a hundred and fifty years ago by the caliph, so that he could rule the most prosperous and best-governed land in the west in a manner befitting its grandeur. The whole civil service was moved out here. There were mosques, baths, workshops, stables, gardens, houses.'

'And,' Ibn Hafsun said, faintly mocking as always, 'there was a menagerie stocked with exotic animals from Africa and Asia, and an aviary, and fishponds like lakes.'

Orm said, 'So if it was all so magnificent, what happened?'

Ibn Hafsun said, 'The Berbers smashed the palace up. Those black-eyed savages of the desert.'

'I blame al-Mansur, who brought the Berbers here from Africa in the first place,' said Sihtric.

'He who stole the bell of Saint James,' Robert said.

'Yes. A vizier who, under a negligent caliph, built a private army, gorged on wealth, and attacked the Christians. And in doing so he fatally undermined the caliphate itself. Al-Mansur! What greed! What arrogance! What folly! What suffering he caused!'

'The people loved him, of course,' Ibn Hafsun said drily.

Moraima said to Robert, 'It is said that the fish in the ponds needed twelve thousand loaves of bread every day to feed them. Maybe they should have employed your Jesus as a baker, just as when He fed the five thousand!' She laughed gaily.

Robert grew hot. 'That's blasphemy.'

Sihtric said, 'Yes, well, the Pope's a long way away. Come now, we're keeping the vizier waiting.'

They rode on.

One part of the ruined palace compound had been roughly walled off. They left their horses here and were met by a servant, a shaven-headed man of perhaps forty, who led them further on foot. The servant said nothing, but treated the Christians to withering looks of contempt. Robert grew angry, but Orm whispered, 'Smooth as snot, isn't he?' That made Robert laugh.

Some effort had been made to restore the buildings in this part of the compound. The paths and patios had been cleared, and the ponds scraped clean of rubble. But there was no water, save that brought in pots by servants from the river. The Berbers, in their gleeful orgy of destruction, had wrecked the aqueducts that had once fed the clogged fountains.

They were brought through a series of rooms which were more or less intact. They were box-shaped, almost cubes, with open archways connecting one to the other, so that for Robert it was like wandering through a puzzle. The walls were covered with fine tiles up to about shoulder height, and above that the surface was rich with filigree and intricate plaster mouldings. The arches especially, some of them double or triple, were very finely made. All the rooms gave onto a patio or a garden, and the bright light reflected through the arches, filling the rooms with a golden glow. It struck Robert that there was not one human image to be seen in the decoration, not one face or figure. But the Prophet's words were etched in long stripes around the walls and over the curves of the arches, so each room was like a page from a vast book. It was a written building.

These rooms weren't perfect. In all of them there was scarring, the scorch of fires, damage to the tiling, holes in the ceilings. But still the maze of beautiful rooms somehow drew out Robert's spirit.

And the soft, indirect light washed over the smooth perfection of Moraima's skin. He smiled, and she smiled back.

So they were brought into the presence of the vizier Ahmed Ibn Tufayl. This was the best room of all, Robert thought. Hangings of Damascus silk covered the upper walls, lamps of silver and crystal gave out a pure light, and an ornate ceiling sparkled with what looked like stars, studs of coloured glass embedded in polished wood.

The vizier himself lay on a couch. 'Sihtric, my friend and colleague. Welcome.' He was a thin, elegant man of perhaps fifty, with a pale colouring, though his nose and cheeks were blotched red. Servants, or guards, stood to either side, scimitars showing at their waists.

Led by Sihtric, the party approached the vizier one by one. Sihtric bowed before him and kissed his hand. Ibn Hafsun followed suit, and then Orm. Robert saw, though, that his father treated the two guards to a challenging stare. Orm was here as an equal, not a supplicant.

The vizier greeted Moraima more tenderly, patting her hair and cupping her cheek. Moraima submitted passively. Robert felt a stab of jealousy, but the vizier's attention was more affectionate than lustful – like a relative, not a lover.

At last it was Robert's turn. Ibn Tufayl's eyes were watchful but bloodshot. When Robert bowed to kiss his hand, on the vizier's fingers he smelled spices and perfumes, but an underlying stink of piss. And Robert was faintly shocked to smell wine on the vizier's breath.

Ibn Tufayl waved a hand. 'Sit, please.'

There were no seats, only couches, and a scattering of cushions on the floor. Sihtric and Moraima and Ibn Hafsun sat cross-legged with the ease of long practice. Orm and Robert followed their example, Orm stiffly. Servants circulated with drinks and sweetmeats, the juices of crushed fruit, and dried figs and grapes.

When Ibn Tufayl spoke, in clear Latin, Robert was surprised it was to him. 'So you're the Christian soldier I've heard so much of from Sihtric. Mother a mystic, father a Viking warrior – yes? A potent mix in young blood.'

'Now, you mustn't tease him, Ibn Tufayl,' Sihtric said. 'His faith is strong. He's probably the purest Christian here – purer even than me.'

Ibn Tufayl arched an eyebrow. 'Well, that isn't hard, Sihtric old friend, as you and I both know. But you don't know much about us infidels, do you, boy? I can tell from your round eyes.'

'I've never seen a place like this before,' Robert blurted.

'Of course you haven't. Beautiful, isn't it? And of course it was far more so before the fitnah. By which I mean the turbulence, the fall of the caliphate. I am determined to restore what I can, before the memory of it is lost.

'This is not like your architecture, boy, that you inherited from the Romans, or that your ancestors brought with them from the German bogs. My ancestors were people of the east, of the sun, of the desert. They came to Spain only a century after the death of the Prophet. They had been nomads; they lived in tents! And their architecture reflects that. Think of this room as a fine tent of stone. To do business we sit on the floor, or lean on the walls – which is why they are tiled to your shoulders. The arches let the light and warmth of the world seep in. And in the patios water played, cherished, for in the desert water is the most precious substance of all.' He sighed. 'Some day it will be restored as it was, but perhaps not in my lifetime.'