Petuaria became the Civitate for the Parisi. The Archaeological evidence is by no means complete on this site. It is clear that it was a walled town or settlement. Some reports reference it as an early fort and naval base, and that it became a Civitas, the capital of the terrritory of the Parisi. The archaelogical finds do not indicate substantial structures to warrant the Civitas status, and there are a paucitiy of military finds. The listed Archaelogical report is worth reading.
http://www.pastscape.org.uk/hob.aspx?hob_id=63928
http://en.wikipedia.org/wiki/Petuaria