Her entrance was an arch with detailed stucco paintwork, though much of the paint had faded and cracked away. She passed through and found herself inside the hollowed-out belly of the great building, a maze in three dimensions of corridors and staircases up and down which people trooped—the big radial staircases were graphically called vomitoria. But Regina’s ticket kept her on the ground level, and led her along a short corridor, deeper into the guts of the complex.

She emerged into daylight, and a wash of color and noise.

She found herself in a small concrete box lined with wooden benches. There was nobody else here; she sat down tentatively, on the end of a bench. She was surprised to find herself here, for she knew that these boxes were reserved for the Emperor’s family, and for senators, magistrates, priests, and other notables.

She was in one of a series of boxes set just above the level of the wooden floor itself. Around her, the arena was a tremendous elliptical bowl. Behind her, rows of wooden seats rose up in four great terraces. The seats were quickly filling up, and the faces of the people receded to mere dots in the shadows of the upper tiers.

She saw workmen on the perimeter of the stadium’s huge open roof. They hauled huge sheets of cloth over a spiderweb of ropes suspended over the gaping roof itself: this awning would shelter the spectators from the sun. It was said that the workers were sailors from the docks, a thousand of them brought here for their skills in working rigging and sails.

And when she looked across the floor to the far side of the arena, the people in those distant seats merged into a sea of movement, color, and flesh, a mob ordered by the amphitheater’s vast geometry. In one glance she could take in twenty thousand people—perhaps four times the population of old Verulamium, as if whole cities had been picked up and shaken until their human inhabitants had tumbled out into this gigantic dish of marble and brick.

On the arena floor the spectacle had already started. To the blaring music of trumpets and an immense hydraulic organ, a parade of chariots raced around the floor, each bearing a gladiator dressed in a purple or gold cloak. They were chased by slaves carrying shields, helmets, and weapons. The crowd began to roar for their favorites. Though the arena was not yet full the noise was already powerful—exhilarating, terrifying—and the air was full of the scent of wood chips, blood, and sweat, making Regina shiver.