But the system threw up dilemmas, such as now. Brica’s fecund days were over, and a new mother must be found.

“I suggest Agrippina,” Leda said. “Brica’s first daughter,” she went on to note, in case Regina needed reminding. “She has been patient since—”

“Since the day I ruined her life?” Regina cackled again. “I hear the mutterings.”

“Six years,” Venus said, “of coping with one little sister after another. Perhaps it is her turn.”

“No,” said Regina thoughtfully. “Let it be Julia.” Agrippina’s younger sister.

Leda frowned. “Agrippina will be disappointed.”

Regina shrugged. “That’s not the point. Think about it. Let Agrippina be the first of the Order to go through an entire life devoted not to the selfish demands of her own body, not to her own daughters, but selflessly to her sisters. An entire life. She will be a model for others, an inspiration for generations to come. She will be honored.”

Leda and Venus exchanged a glance. Regina knew they didn’t always understand her edicts. But then Regina didn’t always understand them herself.

“All right.” Venus stood up. She was heavily pregnant herself, again, and she winced as she hauled herself to her feet. “But, Regina, you can tell Agrippina—”

A messenger ran into the peristylium, flushed and excited, interrupting the women. Regina had been summoned to the imperial palace.

When she took herself out of Council meetings and the like and just walked around the growing Crypt, it sometimes startled Regina to realize there were already thousands of people involved in the Order, in one way or another.

She thought of the Order as like the bulb of a fine fat spring onion. At its heart was the family: the descendants of the sisters Julia and Helena, now both long dead, and their descendants, including Leda, Venus, Regina herself, and Brica and her children. Aside from them, at any one time there were hundreds of students living either in the Crypt itself, or in the buildings the Order maintained overground. Beyond that there were workers with peripheral connections to the Order: for example, the peripatetic teachers and orators, the miners who tunneled steadily underground, even bankers and lawyers who managed the Order’s income and investments. And then there was a more diffuse outer circle of those who simply contributed to the Order, in cash or in kind: the families of students paying their fees, former students gratefully contributing through gifts or legacies to the establishment that had educated them so well.

But in all this, the safety of the central family was paramount. That had been Regina’s goal when she had sacrificed her relationship with Brica to get her out of Britain and bring her here, and that was her goal now.

She was satisfied with what she had done so far. But of course everything was temporary. The Order didn’t have to last forever — just long enough to shelter the family until things got back to normal. And she was becoming convinced that, yes, she had stumbled on a system that would work to achieve that goal.

Her own end could not be far away. She knew that from the dreadful weakness she felt in the morning, her unfortunate habit of coughing up blood — and the disturbing sensation of a hard, immovable mass in her belly, like a giant turd that would not pass out of her system. It was just like the illness that had taken Cartumandua, she remembered. She did not fear her own death. All she feared was that the system might not be completed before she was gone. What had she missed? That was the question she asked herself every day. What had she missed? …

She had no idea why the Emperor wanted to see her, but she could scarcely refuse him. So, on the appointed day, she walked alone across the city.

Rome had decayed visibly, even in the time she had lived here.

Many of the aqueducts and sewers were in urgent need of repair. The public granaries were closed. Many monuments and statues had been looted and violated — indeed, people stole stone from them either for building projects of their own, or simply to burn the marble for lime. The drainage of some of the fields beyond the city walls had failed, and they were degenerating into swamps. Sometimes you would see dead cattle drifting down the swollen waters of the Tiber, and starvation and disease routinely stalked the poorer parts of the city. Many of the rich had fled to the comparative comfort of Constantinople; many of the poor had died.

Regina was dismayed, but she had seen it all before. It was Verulamium or Durnovaria writ large. But still the Forum and the markets swarmed; even now it was a great city. And this was Rome; even now she was sure its mighty lungs of concrete and marble still swelled, and the city would recover.

And as Regina approached the imperial palace on the Palatine Hill, even seventeen years after arriving in the city, she was awed.

Itself three centuries old, the palace had been the residence of emperors since Domitian. It sprawled across the whole central portion of the Palatine, a complex of buildings several stories high, roofed by red tiles and coated in decorative stones of many colors. The imperial residence itself was said to be the size of a large villa, with baths, libraries, and several temples — even a private sports stadium — and yet it was lost in the greater maze of buildings. The palace was like a small town in itself, a sink toward which the resources of a continentwide Empire had once flowed.

She was met by a retainer in the Via Sacra, to the northeastern side of the complex. She held her head up, ignoring the nagging pain inside, determined to show no weakness. She was led through two great arches, dedicated to the memories of the emperors Titus and Domitian, and found herself in a large paved area. It was the Domus Flavia that was her destination, the wing of the palace where official work was done.

The Domus Flavia was built onto a large platform set on top of the hill. It consisted of several rooms set around a huge peristylium. The walls and floors were decorated with mosaics and imported stones; the colors were bright yellow, crimson, and blue, the lines of the rectangular patterns sharp. There was much business being done here, she saw; men walked this way and that, arguing earnestly, bearing heaps of papyrus scrolls or wax tablets. Despite the bustle, as with much of Rome there was a sense of shrinkage, of emptiness, as if these busy men were smaller than their ancestors. She wondered how it must have been two or three hundred years ago when this building really had been the hub of the whole world.

A fountain set in the center of the peristylium was dry, its bowl mildewed, evidently long out of action. It made her think of her own long-lost childhood home; the fountain had never worked there, either.

“Madam. I am Gratian.” The man who greeted her was tall, his hair white as British snow, with a thin, strong-nosed, elegant face. He was actually wearing a toga, a sight rarely seen nowadays. Gratian walked her toward one of the great buildings. It was a throne room; he called it the Aula Regia. “We will sit in the shade, over wine …”

Gratian was a senator, a close adviser to the Emperor — and a close relation. He was one of the cabal of rich and powerful men who actually controlled the imperial administration: though the Emperor Romulus Augustus bore two of the mightiest names in all Rome’s long history, he was but a boy.

If the complex as a whole was impressive, the throne room was startling. The walls and floor were covered with a veneer of patterned marble, gray, orange, brown, green. The walls were fronted by columns, and in twelve niches stood colossal statues carved of night-black basalt. The room was covered by a vaulted concrete roof, and was oddly chill even in the heat of the day. The floor was warm, though, evidently heated by a hypocaust. At one end of the room was an apse where the Emperor received embassies and gave audiences. Today it was empty.