Chester is arguably the richest city in Britain for archaeological and architectural treasures preserved to this day from the time of the Roman occupation. Originally the fortress site of the 20th legion (Valeria Victrix) it was charged with suppressed the uprising of the army led by the warrior queen, Boadicea, the town being known then (c. AD70) as Deva, and soon became a major trading port. Its massive harbour and border position made it one of the finest strategic outposts of the Roman Empire. Long after the Romans had gone, during the Dark Ages, Viking raiders arrived in their long boats along the same route. After the Romans withdrew circa AD400, the prosperous city fell prey to marauding Danes and Saxons and was virtually derelict by 900. The Normans reached Chester circa 1070 and a revival began, Chester Castle was built, housing Hugh the Wolf, First Earl of Chester, nephew of William the Conqueror. By the Middle Ages, Chester had become an affluent and prosperous port. It was during this time that the famous Rows were built. so that by the 13th century, it had again become a centre of shipping trade, a port serving Scotland, Ireland, France and Spain. In the 14th century began the Mystery Plays and pageants for which the city became famous. Henry VIII granted a charter in 1541 and made Chester a bishopric. By the 15th century, the Dee began to silt up and gradually, the seaborne trade died. Impoverished by this natural action the 1640s brought devastation during the English Civil War, with the city under siege for two years until starvation forced surrender. But throughout this chequered history, the Roman walls remained virtually intact. The walls extend in a 2 mile circuit and give a vivid reminder of what a medieval fortified town was like. In the Middle Ages, several towers and gates to the walls were made: the most important of these was at Eastgate, now astride a main throughfare and crowned with an anachronistic clock commemorating Queen Victoria's diamond jubilee (1897).