"What's going on?"

I turned my head; startled. "Diana, go back down the ladder at once!"

"Why? Is it dangerous up here?" "Very. Your mother would have a fit."

"Oh, I hardly think so. She held the ladder for me. But I think she's afraid to come up herself." "As well she might be."

"And how about you, Papa? I should think an old fellow like you would be more likely to lose his balance than I would be."

"How did I ever come to have such an impertinent child?"

"I'm not impertinent. Just curious. It's like the siege of Troy, isn't it?"

"What?"

"Like Jupiter up on Mount Ida, watching the battlefield down below. They're all so tiny. It makes one feel… godlike."

"Does it? Jupiter could send down thunderbolts or messengers with wings. And he could hear what was being said. Having a view hardly makes me feel godlike. Quite the opposite. It makes me feel powerless, watching from a distance like this."

"You could go down and join them."

"Put myself at the mercy of that mob? There's no telling what they might do next -" "Papa, look!"

Like a storm-churned flood, the crowd seemed suddenly to overflow the broad square in front of the Rostra, surging in wave after wave onto the steps and terraces of the surrounding temples and public buildings.

"Papa, look! The Senate House!"

The broad steps were inundated by the mob, which rose like a black flood tide to lash against the tall bronze doors. Bolted from within, they stood against the tide, but soon I began to hear a low, thudding, repetitive boom. It was hard to see exactly what was happening, but the mob seemed to be assaulting the doors of the Senate House with some sort of makeshift battering ram.

"Impossible," I said. "Incredible! What are they thinking of? What do they want?"

All at once the doors gave way. A moment later a cheer of triumph rose from the crowd. I looked back to the Rostra. The speaker was still ranting, striding back and forth and exhorting the mob with wild gestures, but the body of Clodius had disappeared. I frowned; puzzled, then caught sight of the naked body on its black-draped bier proceeding with odd, jerky movements towards the steps of the Senate House. It seemed that the mob was passing the bier from hand to hand above their heads. I suddenly had a vision of the mob as a colony of insects, and the corpse of Clodius as their queen. I shivered and felt an intimation of vertigo. With one hand I reached for Diana, putting my arm around her shoulder, and with the other I held more firmly to the tiles of the roof.

The bier reached the foot of the Senate House steps, stalled for a moment, then tilted upward and began to ascend. The mass of the crowd, able to see the body again, produced another loud roar of mingled triumph and despair. The bier reached the top of the steps and was propped upright. A man stepped up beside it, waving a burning torch. He seemed to be giving a speech, though it was hard to imagine that the roaring crowd could hear him any better than I could. Even at such a distance, I was almost certain that the speaker was Sextus Cloelius, Clodius's wild-eyed lieutenant, the man who had spoken of riots and revenge against Milo the previous night.

After a while, still waving his torch, he turned and entered the Senate House. The bier was carried in after him.

"What can they possibly be thinking?" I said.

" 'Burn it down,' " said Belbo. "Wasn't that what the fellow said, the one who pounded on the door?"

I shook my head. "He was raving. Besides, he must have meant burning down Milo's house, or maybe Cicero's. He couldn't possibly have meant…"

Sometimes, uttering the impossible can suddenly make it seem quite possible after all. I stared at the roof of the Senate House, as if by concentrating I could see through it to perceive what Sextus Cloelius was up to. Surely not -

And then I saw the first wisps of smoke, streaming wraithlike from the shuttered windows set high along the walls of the Senate House.

"Papa-"

"Yes, Diana, I see. They must be cremating the body, inside the building. The idiots! If they aren't careful -"

"They hardly look to me like the sort to be careful," said Belbo, tilting his head earnestly.

A little later the first flickering tongues of flame appeared at one of the windows. One after another the shutters caught fire. Heavy black smoke began to pour from the windows, then from the open doorway. Sextus Cloelius ran out of the building, waving his torch triumphantly over his head. The crowd fell silent for a moment, probably as awed as I was by the enormity of what had happened. Then they released a roar that must have been heard all the way to Bovillae.

It was heard in Cicero's house, at least. From the corner of my eye I saw a movement on his roof He had returned, along with Tiro. The two of them stood upright, no longer crouching, and watched the spectacle in the Forum below. Tiro clutched his face. He was weeping. How many happy hours had he spent in that building, copying down his master's speeches in the shorthand he invented, ordering his army of clerks about, paying witness to the great career he had done so much to foster? Slaves can be very sentimental.

Cicero did not weep. He crossed his arms, set his jaw in a hard line and stared grimly at the orgy of destruction below.

"There!" said Diana. She was pointing at Cicero. "There! That's what Jupiter must have looked like, gazing down at Troy."

Knowing Cicero far better than my daughter did, and certain that there was nothing remotely godlike about him, I was about to correct her when Belbo interrupted.

"You're right," he said. "The very image!"

Their shared certainty forced me to take another look. Diana was right. I had to concede it. As Cicero looked at that moment, watching the destruction of the Senate House by Clodius's mob, so great Jupiter might have looked when he brooded on Mount Ida and watched the mad clash of mortals below.

Whipped by the cold wind, the blazes shot higher and higher until the whole Senate House was engulfed by flames. The mob danced on the marble steps, hooting and laughing while they dodged cascades of cinders and ash.

The fire began to spread, first to the complex of senatorial offices to the south of the Senate House. The threat of the mob had already emptied most of the buildings, but after the flames started a few panic-stricken clerks came rushing out, carrying armloads of documents. Some tripped and fell, others zigzagged madly, dodging the taunting mob, dropping their burdens. Wax tablets scattered like tumbling dice. Scrolls unfurled and streamed like pennants in the breeze.

Then the wind changed. The flames spread west of the Senate House, to the Porcian Basilica. One of the great buildings of the Forum, it was a hundred and thirty years old, the first basilica ever built. Its distinguishing features – the long nave terminating in an apse with colonnaded aisles on either side – are now duplicated in buildings all over the empire. Many of the wealthiest bankers in the world kept their headquarters in the Porcian Basilica. It took hardly an hour for the fire to reduce its venerable majesty to a smouldering pile of rubble.

It was the bankers, I learnedlater, desperate to salvage what remained of their records, who finally organized a large contingent of freedmen and slaves to battle the flames. Acting out of pure selfishness, they may have saved a large part of Rome from going up in smoke. The firefighters formed long, snaking lines across the Forum and through the cattle market all the way to the banks of the Tiber, where they filled buckets with water and passed them up to pour on the flames, then passed the empty buckets back again. From time to time a few rowdies broke away from the mourners' frenzied revelry to harass the firefighters, pelting them with stones and spitting on them. Scuffles broke out. A cordon of bodyguards, also sent by the bankers, arrived to protect the bucket-passers.