On the Tigris River, the ancient city of Samarra contains a series of medieval structures that hold secrets to one of the world's greatest empires, the Abbasid Caliphate; now, archaeologists use pioneering technology to investigate its astonishing rise to power and reveal its monumental downfall. 

The coliseums of Rome were brutal theaters of spectacle and death that helped control the sprawling Roman empire; now, archaeologists uncover the engineering secrets behind these more than 230 majestic structures to reveal the truth behind the ancient Roman world.