The British royal residence Windsor Castle was built in which century?

Windsor Castle is a royal residence at Windsor in the English county of Berkshire. It is strongly associated with the English and succeeding British royal family, and embodies almost a millennium of architectural history.

The original castle was built in the 11th century after the Norman invasion of England by William the Conqueror. Since the time of Henry I (who reigned 1100–1135), it has been used by the reigning monarch and is the longest-occupied palace in Europe.

Windsor Castle grounds cover 52,609 square metres (13.000 acres) and combines the features of a fortification, a palace, and a small town. The present-day castle was created during a sequence of phased building projects, culminating in the reconstruction work after a fire in 1992.