Built at strategic points, and fitted with impressive fortifications and ingenious systems to counter attacks, fortresses are thought to be impenetrable. And yet, certain skillful warlords have successfully stormed them. How did they manage this?

By recounting how some of the most remarkable sieges - in ancient times or in medieval history - played out, this series revisits the construction of these megastructures and reveals the different strategies used to lay or to endure a siege. Thanks to CGI, dramatized scenes, and with the help of key experts, it immerses us in the compelling confrontation between the construction genius of the military strategists and the ingenuity of some exceptional warriors.