The Romans arrived at the spot where the Rivers Ouse and Foss meet in AD71.

They quickly set about building a sound set of defences as the local tribe - the Brigantes - were not very friendly.

We know how the fortress would have looked. This is partly due to excavation results and partly from looking at other fortresses of the same period.

The first defences were simple: a ditch, an embankment made of turf and clay, a large timber fence, and timber towers and gates. Inside was a simple pattern of streets and buildings.

The fortress was big. You could comfortably fit 50 football pitches inside the defences (20.3 hectares for the technically minded).

A large and important town grew up around the fortress over the following 150 years. It centred on the south-west bank of the River Ouse.