Historian Sam Willis traces the story of Britain's castles and their unique role in our history, art and literature.
Sam Willis shows how the castle arrived as an instrument of invasion with the Normans but became a weapon with which unruly barons challenged the Crown.
Sam Willis tells the story of the English ruler who left the most indelible mark on the castle, Edward I, as he turned it into an instrument of colonisation.
Sam Willis looks at how castles survived into the Tudor era. But these strategic seats of power had to become palaces to impress monarchs such as Elizabeth I.