'Fort of the Larks,' said the Emrys. That is what this place was called. Long have the larks enjoyed the use of it. Now it belongs to Arthur.'

It was his voice that fascinated me. Infinitely expressive, it served him in any manner he wished. When he lashed, it could have raised welts on a stone. When he soothed, it could have shamed nightingales into silence. And when he commanded, mountains and valleys exchanged places.

After we finished our meal, he took me inside the rotunda, which was even more remarkable than its exterior. For, rather than the cold, dark, cave-like appearance I expected, the interior was open, airy and light. The domed roof remained open to die sky, providing ample light to pour down gently curving sides of dressed white stone.

The Great Emrys spread his arms and turned slowly, indicating the perfect circularity of the shrine. 'This,' he said as he revolved, 'this is the Omphalos of Britain.'

As I remained silent, he asked, 'Have you never heard that word before?'

'No, Lord Emrys, I have not.'

'It is the sacred centre. All things have a centre – for the Kingdom of Summer, the centre is here.'

I pondered this for a moment. 'I thought – ' I began, 'that is, I heard that Ynys Avallach held that prominence.'

The Glass Isle? No,' he shook his head, 'I know what men say of the Tor, but that belongs to another… '

Another what, he did not say. 'Besides,' he continued briskly, 'the Fisher King is not long there. There are too many people nearby – the south is becoming too crowded. I have prevailed upon Avallach and my mother to establish themselves in the north.'

I knew of the Fisher King, and Charis, the Lady of the Lake, next to Gwenhwyvar reputed to be the most beautiful woman in Britain. 'They are coming here?'

'Not here, but near. There is an island where Arthur has granted them lands,' he told me.

I slept that night in one of the workers' tents; the Emrys slept in the rotunda. In the morning I awoke, took my broom and went up to him. He greeted me and bade me enter.

Hesitantly, I stepped up to the entrance and glanced around the inside of the shrine. In the centre, beneath the all-seeing eye of the open dome, sat an immense stone chair, or throne, carved of a single slab of living rock and placed on its own raised table of stone. The curved inner walls were ledged with a series of ringed stones, hundreds of them, each one forming a small niche of its own. It seemed to me much like the bone-houses of elder times with their skull nooks – crevices carved out of stone to hold the severed heads of venerated ancestors.

All appeared finished, the white stone gleaming. 'What would you have me do, Lord Emrys?'

'Sweep,' he told me. The Emrys turned to a table, unwrapped a leather pouch that lay there, and withdrew tools: an iron hammer, a chisel, and a scribe for marking stone. He took up the hammer and turned once more to the nearest stone ledge and began inscribing letters on the smooth face.

'A name, Lord Emrys?'

'The names of those who have attained the Round Table will be recorded here,' he explained. 'Those who have distinguished themselves in the service of the Summer Realm will have their names cut in the stone. When death finds them, that will be recorded too, and their bodies buried within the sacred precinct, so that their renown will not pass out of this worlds-realm.'

Understanding came to me at last. The tabled rotunda was to be a place of spiritual refuge, a haven of tranquillity dedicated to the Prince of Peace, a reliquary of great holiness and honour, where the names and arms of great men could be venerated, a memorial to deeds of courage and valour.

Thus, I entered my servitude. I swept, carried water, gathered firewood, tended the camp and, when I was not otherwise occupied, washed the stone – time and again I washed it. When I finished, I swept the interior of the rotunda and washed it again. I scrubbed it till the stone gleamed.

Daily the food came. Sometimes in the morning, when we rose, I would go down to the stream below the hill and fetch it from the hollow bole of a willow. Other times we would emerge from the shrine, hungry from our work, to find the wcven-grass bundle on the topmost step. Never did I see those who left it, nor could I guess whence they came.

Day by day, the names were chiselled into stone. Some of the names I recognized, most I did not. Sometimes the Emrys would tell me about the man whose name he etched. More often, we worked in silence. But it was never a lonely silence. I knew the Emrys' thoughts were full, as were my own. Just being near him proved instructive and edifying. Still, I liked it best when he sang.

After a while, I little noted the passing of the days. My hands grew strong and tough. My life was a steady-beaten rhythm of work and rest. I desired nothing more. When one day I heard a call outside, I actually resented the interruption, although I had seen no other human being besides the Emrys since the day I arrived.

The Emrys laid aside his square and scribe. That is Tegyr with a message. Let us see what he brings us.'

It seemed an intrusion, but I reluctantly put down my broom and followed him out. Tegyr was there at the foot of the hill, and someone else with him: a warrior, I could tell by the size of him. One of Arthur's captains, I guessed. He was dark, with deep-set eyes and a high, handsome brow. There were scars on his arms and hands, and on his left cheek.

"The battlechief regarded me placidly before turning his attention to the hill and the shrine, now cool blue-white in the westering sun. 'Hail, Myrddin Emrys!' he called, as we approached. 'What is this I am hearing about you? They say you have gone into your invisible fortress and will never more return.'

'Hail, Bedwyr!' cried the Emrys. 'It is that much like you to believe the idle gossip you hear.'

The two embraced like kinsmen and, Unking arms, began walking up the hill. Tegyr, smiling silently, followed and I came on behind.

'It is beautiful,' breathed Bedwyr. Truly beautiful. Arthur will be honoured. And the queen will establish a perpetual choir to sing your praises!'

'Has Gwenhwyvar returned?'

'Yes. Tegyr said you asked him to bring word when she arrived, so I thought to come with him. I wanted to see what you had accomplished since I was last here. Do you object?'

'Never – besides, we are nearly finished as you can see. I will return with you to Caer Lial tomorrow.'

I listened to their talk and learned that the queen had been away in the south, helping with the Fair Folk migration from Ynys Avallach to the chosen island in the north. Arthur meantime held council at Caer Melyn and Caer Lundein. He was not expected to return before Lugnasadh. This would give the queen time to make her last inspection of the monument, and to arrange the ceremony and celebration of its completion.

Bedwyr and Tegyr spent the night with us and all of the next day, while the Emrys finished his work. All three left the following day, but I stayed at the rotunda to sweep out the last of the dust and stone-chips, and wash the floor and ledges. The Emrys was to return in two or three days with the queen.

As soon as the others left, I worked through the day without cease until finishing. It was dusk when I finally sat down to rest and eat. Though the sun had set long before, the sky at that time of year does not grow completely dark. Therefore did I enjoy a pleasant evening – sitting alone on my hill, monarch of all I surveyed, watching sea-gulls dive and glide in the clear evening air.

I had not made my fire. There was light enough yet, and the night chill had not settled on the hill. I ate my sweet dark bread and cold roast mutton, and then rose to find my water jar. I had left it inside the shrine, so went in to fetch it.

The interior of the rotunda was dark now, but I had little trouble finding the jar. I drank my fill and turned to go outside. As I turned, however, a figure appeared in the arched doorway – dark against the lighter sky beyond.