Meet the Castle Builders - the masons and laborers who did the hard work; the geniuses of design and structural engineering who imagined these medieval mega-structures; and the kings and barons who commissioned them.

This is the story of castles under attack. The Medieval journey from bows and arrows to gunpowder, with developments like trebuchet and cannon, meant engineers were always making advancements in defense construction.

Increasingly the role of castles changed from being military fortresses to becoming places of symbolism and fantasy. This episode traces the changes to Windsor Castle under Edward III, when it became an icon of regal glory.