Colchester Castle is a monumental Norman keep built by William the Conqueror around 1076 to establish control over newly conquered territory, constructed with stone salvaged from the underlying Roman Temple of Claudius. The temple itself, built between AD 49 and 60, was the largest in Roman Britain and represents some of England's oldest surviving Roman stonework. As Europe's largest Norman keep, the castle has served as royal fortress, stronghold, and prison throughout the medieval period. Today functioning as a museum, the castle displays one of Britain's most significant archaeological collections, including Celtic coin hoards, Roman statues and mosaics, medieval artwork, and Civil War artifacts. Colchester Castle offers visitors a remarkable journey spanning over 2,000 years of architectural and cultural history from Roman to Norman periods.