who build it?
William the Conqueror.
Windsor Castle
The original castle was built in the 11th century after the Norman invasion of England by William the Conqueror.
when does the queen stay at windsor castle UNANSWERABLE when was it build ? 11th century.
wiki:8897554
Windsor Castle [SEP] Introduction
Edward's core design lasted through the Tudor period, during which Henry VIII and Elizabeth I made increasing use of the castle as a royal court and centre for diplomatic entertainment.