The site of a major oppidum, the name means the walled town of bridges. It was enclosed in a turf wall in the late 2nd century which was replaced by a stone wall C. 225. Parts of the stone wall were incorporated into the Mediaeval town walls.
http://www2.rgzm.de/transformation/unitedkingdom/smalltowns/Img04.htm
http://roman-britain.co.uk/places/durobrivae_cantiacorum.htm