The English County of Berkshire
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Windsor Castle in Berkshire is one of three official residences of the British sovereign. Unlike the other two, Buckingham Palace and Holyrood in Edinburgh, it has from its earliest days been a fortress as well as a palace. The castle owes its shape and its earthworks to the work of William the Conqueror, although the round tower on the great natural chalk mound or motte was built later, chiefly by Edward III.