Historian Simon Sebag Montefiore uncovers the central role played by religion in creating and maintaining the power of the city of Rome from its foundations to the modern day. From its founding myth and its pagan gods whose actions dictated the politics of ancient Rome to the time that a new cult from the East, Christianity, threatened the status quo. In the first episode we see how every event in ancient Rome revolved around religion. From the foundation myth through to the deification of Emperors; nothing could happen without calling upon the Pantheon of Roman gods. Simon investigates how the Roman's worshipped and sacrificed to the gods. He discovers that sacredness defined what was Roman and it was the responsibility of every Roman to play their part in the cult.