Our current read is set in the Roman city of Glevum, or more formally Colonia Nervia Glevensium. Wikipedia has an article on Glevum (usual caveats apply).
roman-britain.org has its usual thorough coverage, including a picture of a mosaic found in the city - not, alas, by Libertus as it has been dated to the fourth century. The Gloucester city website has some pages on the Roman period, including this page from a virtual tour of the city museum. The city museum's own website has pictures of sculpture found in the city and roundabout.
As the city's full name indicates, it was the Emperor Nerva who gave the town the status of a colonia. As part of its celebrations of its nineteen hundredth anniversary the town erected an equestrian statue of Nerva.
