Tarcho grew more animated. He pointed out forts and camps and watchtowers that were part of a ‘deep defence system’, he said, reaching far back into the countryside south of the line of the Wall itself. And the land was studded by big blocks of greenery at the crowns of the hills and in the valleys. They were managed forests, planted especially to provide the Wall with timber for its baths and ovens. While the Wall was here to defend the country from the savages in the north, the country had to feed the Wall. Audax began to think of the Wall as a great ravenous beast, sucking the blood from a cowering land.

They arrived at last at a place called Banna, where there was a fort.

Before it reached the fort itself the road snaked through a patch of farmland owned by the fort - the ‘soldiers’ meadow’, Tarcho called it - and the party crossed over a ditch clogged with weeds and stinking rubbish.

Then they passed through a kind of town, sprawling east and west along the road outside the fort walls. The roads were more like sheep tracks than Roman roads. The place was noisy, smelly, crowded. Some of the buildings were quite smart and built to square plans, but the rest were just shacks. Many of them had open fronts, and Audax peered into shops where metal was worked or cuts of meat were piled high. There were soldiers, dressed in military belts or bits of armour like Tarcho’s. But there were plenty of women, and children ran everywhere, getting in the way of the horses. Audax liked it better than Camulodunum. It seemed a cheerful place. But Tarcho hurried him past the soldiers’ taverns, gambling dens and brothels.

At last they approached a stone wall. This was the fort itself. The buildings of the scrubby town outside lapped right up to the wall. At the fort gate they had to pay a charge, and the carriage was searched for weapons.

Inside the fort Audax was overwhelmed by a stink of blood and smoke and piss. Tarcho told him it was always like this; the soldiers used their own urine to cure leather for their armour and harness gear. Though Aurelia and Cornelius pressed bits of perfumed cloth to their noses, Tarcho opened his chest and sniffed in the foul air through his big, black, snot-crusted nostrils. ‘Home! Nothing like it.’