Nestling halfway between the mediaeval town of Shrewsbury and the birthplace of the industrial revolution at Ironbridge, lies Viroconium -- once the fourth largest city in Roman Britain. While its three greater fellows -- London, Cirencester and St. Albans -- have all undergone considerable further development in subsequent ages to yield an amalgam of historical overlays, Viroconium was simply abandoned sometime in the 5th or 6th Century.
...Whether Viroconium really was the Camelot of legend or whether some other local prince or king carved a domain for himself amid the remnants of the old capital of the civitas Cornoviorum* will perhaps never be known..
Whoever and whatever its most recent occupant may have been, the city is believed to have been finally vacated sometime between AD 500 -- AD 650.
Been there. I love ancient Roman ruins in England. Plan on returning next year for a visit. Spent 3 years there during my USAF career. Best years of my USAF career.