It was this way from end to end of the Empire, across two thousand miles, from Britain to the Middle East. The Empire was the most materially sophisticated civilization the western world had yet seen—but the overwhelming majority of people lived off the land, as they had always done.

Aetius spent a long time trying to explain some of this, but he got stuck on the meaning of the word million. Regina’s attention drifted, distracted by the sway of the horses, the clatter of the wheels, the buzzing of flies.

“Oh, stop fidgeting,” Aetius snapped. “If only I could just order you to sit still . . .” He pointed with his switch at a little cylindrical pillar set beside the road. “Well, what’s that? Do you know?”

She knew very well. It was a waystone. “It tells you how far it is to the nearest town, and who the Emperor is.”

He grunted. “Somehow I doubt that poor Honorius has gotten around to painting his name on the stones . . . But, yes, that’s the idea. Now, the stones are set every thousand paces or so along each main road. And if you count them, you’ll know how far we’ve come, won’t you?”

“Yes!” She rubbed her nose. “But what if I fall asleep? Or what if it’s dark?”

“If you fall asleep I’ll count for you. And don’t rub your nose. You have to start now. That’s one . . .”

“One.” Solemnly she folded a finger back as a marker, and peered along the road for the next pillar. But it seemed an awful long time coming, and by the time she saw it she had forgotten what she was supposed to be doing, and had let her finger fold out again.

Her grandfather seemed determined to keep up her schooling, and as they rattled along he told her the story of the road itself. The soldiers from the army of Emperor Claudius had first come this way, surveying the route. The road had been built by the soldiers themselves, and people drafted in from the countryside.

“How much did they get paid?”

“Paid? Hah! Everybody was a barbarian in those days, child. You didn’t get paid. Look. You put down a gravel core, and lay on a surface of crushed limestone. You use stone slabs where you can find them. The water drains out into those side ditches—can you see? . . .”

She was good at pretending to listen, while being occupied with her own thoughts. But eventually she drifted asleep, slumped against Aetius’s sturdy form, dreaming fitfully about the little girl in her hobnailed boots.

She dozed through the day, or listened to Aetius’s complicated talk, or played word games with Cartumandua. They stopped only to water and feed the horses; the passengers ate on the move in the cart, bread with fish and meat.