Meet the Castle Builders – the masons and labourers who did the hard work; the geniuses of design and structural engineering who imagined these mediaeval mega-structures; and the kings and barons who commissioned them. This episode outlines how the history of the Middle Ages –Wars in France and England, the Inquisition and the Reformation, required and shaped these monuments in stone, and how the castles changed the course of that history.

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 defence construction. By the late Middle Ages, the military importance of castles was decreasing, as artillery power became unstoppable. But as we find out, even the siege of Pembroke Castle during the Civil War needed the tactical genius of Oliver Cromwell, not just big guns. The castle builders had created structures that was amazingly effective even in this new age of shock and awe.

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 and a centrepiece for his cult of chivalry – including his famous recreation of King Arthur’s Knights of the Garter. This episode visits the elegant 15th-century apartment block that is Burg Eltz, the Disney-esque chateaux of the Loire in France, and reaches a conclusion with the 19th Century Gothic Revival reconstruction of Cardiff Castle.