Why was Arundel Castle built?

The construction of Arundel Castle began in 1067, by Roger de Montgomery, the first Earl of Arundel. Roger was one of William the Conqueror's most powerful barons, and Arundel Castle was built as a symbol of his power and authority in the region. The castle was built on a strategic location, on a hill overlooking the River Arun, and it served as a defensive fortress against potential invaders.