Karus opened the door to reveal a latrine. Over two rows of holes in the floor people sat on wooden benches, men, women and children alike. Some read letters on bits of wood, others talked, some gambled over dice on the floor between them. One man was bending over to wipe his arse with a bit of sponge on a stick. There was a predictable stink, but it wasn’t as bad as Brigonius might have thought - and then he heard a gurgle of water coming from beneath the holes.

‘Ah,’ he said. ‘A stream runs beneath to take the shit away. Cunning.’

Karus shrugged. ‘More likely the water is piped here from the river to the north. Public water supply, you see. You’d have to ask an engineer; I’m no expert.’

They walked on. They passed a baths - unfinished, but in use, and quite unmistakable to Brigonius from its musty, boggy smell, just like the soldiers’ baths at Vindolanda.

They reached the marketplace. Lepidina, with a squeal of excitement, begged more money from Karus. Soon she was working her way through stalls heaped with jewellery and little bottles of perfume and hair oil. The men walked on.

Once more Brigonius felt overwhelmed. Compared to the rough-and-ready market that had grown up outside the Vindolanda fort there was a bewildering array of goods for sale here: cosmetics of all sorts in little glass jars and bottles, silver and copper pins and brooches, plates and bowls and tiles, stalls heaped with shoes of stitched leather. There were bakers and vendors of broiled meat, and the heat of their ovens turned the air ferociously hot. There were even moneylenders, bankers and lawyers - and many, many bookmakers.

Shoppers thronged. There were plenty of Catuvellaunians, of course. But Brigonius saw Germans and Gauls of the kind the army was full of, and still more exotic types with very pale skin, or very dark, who sold wines and spices for exorbitant prices. They were traders from perhaps far across the empire or even beyond, come here to this corner of Britain to sell their wares. Everyone seemed confident here, happily buying and selling, all of them at home in a place where they knew the rules, all save Brigonius.

And beggars crowded around every stall, silently pleading for change. There were no beggars in Banna; people looked after their own. Brigonius wondered what old Cunobelin would have thought of what had become of his descendants.

More public buildings surrounded the forum. Karus led Brigonius to a great hall whose unfinished walls rose above the heads of the shoppers. They walked through a colonnade of pillars and over a stone floor that was, as yet, unroofed. Brigonius saw that the floor was weather-stained; evidently the building had been in this half-finished state for some time.