City of the Dead: the Roman Town of Calleva Atrebatum. The BBC offers this report by Michael Fulford about Roman Britannia. Field work in Hampshire uncovered the remains of Roman town of Calleva Atrebatum.
The big questions is why this site was abandoned. One theory offered is that the population was primarily Irish and that Anglo-Saxon ethnic cleansing in the 6th Century may have lead to the downfall of the town.
From the site:
The Iron Age and Roman town of Calleva Atrebatum can be found deep in the north Hampshire countryside in the parish of Silchester. But where once there was a busy, populous centre, now there are only green fields. All that is now visible above ground, of a settlement that thrived for more than 500 years between the first century BC and the fifth or sixth century AD, are sections of the late Iron Age fortifications of rampart and ditch, the Roman amphitheatre and, most impressive of all, the entire circuit of the late Roman town walls.
Most Roman towns evolved into modern counterparts, either directly over the site of the ancient city, such as at Chichester, Winchester or London, or close by such as at St Albans or Norwich.
So two very reasonable questions to ask about Calleva are: why did a major settlement develop in this location; and why is there no successor medieval and modern town? There are no certain answers to either of these questions, but trying to resolve them is one of the eternal fascinations of Calleva.