The castle arrived as an instrument of invasion but soon became a weapon used by unruly barons to challenge the Crown. In this revealing documentary, Sam Willis looks at the history of the British castle from the Normans in 1066 to the myths surrounding King Arthur and the knights of the Round Table in Tintagel and the longest siege on English soil at Kenilworth Castle.

One English ruler left an indelible mark on the castle: Edward I. As this gripping history documentary explores, Edward spent vast sums to construct some of the most fearsome fortresses ever built, used to impose England's will on the Welsh. But when Edward turned his attention to Scotland, laying siege to their castles with great catapults, things didn't go so well for him.

Castles, once used to wage war, instead became palaces used to impress monarchs such as Elizabeth I, or ruins that instilled a sense of nostalgia for an age of chivalry in the British psyche. But, as this exciting history documentary reveals, just as castles seemed to have lost their defensive function, the English Civil War erupted, a tumultuous period that changed Britain forever.