Originally viewed as a mysterious cult, find out how Christianity came to be accepted as the official religion of the Roman Empire.

Demonized by ancient sources and portrayed throughout history as a cruel madman -- was Emperor Caligula really insane or just the product of a mad world? He inherited a vast empire, unimaginable wealth and the love of his people, but Caligula's reign descended into paranoia, depravity and full-blown insanity. Using dramatic re-enactments along with expert testimony from a forensic psychologist, NGC investigates: Is there a medical explanation behind his terrifying mind?

Go inside the ancient war machine that was the legion army, the most deadly and disciplined force in the classical world.

Archaeological evidence and eyewitness accounts recreate the Colosseum's opening night, featuring a legendary duel. Beast fights in the morning. executions at lunchtime. Gladiator combat in the afternoon. NGC re-creates the opening days of the Colosseum, the spectacles, the combatants and the monumental structure that housed them. We'll then reveal what went into staging the games and the arsenal of weapons the gladiators had at their disposal -- re-creating the action of the empire's iconic venue.

Over centuries, the Romans transformed a swamp on the banks of the Tiber into a settlement, then a city of brick and ultimately the gleaming marble core of the ancient world's greatest empire. Journey through massive Roman tunnels and trace the city's architectural and engineering evolution, including tombs, temples, monuments and aqueducts. See how the Romans converted an uninhabitable region into the home of some of the most impressive monumental architecture the world has ever seen.

This is the story of a disaster like no other. When Mount Vesuvius erupted, it rained 8 million tons of debris onto Pompeii it sealed the fate of more than a thousand people. But it also sealed the city form the world: preserved it, protected it, like nowhere else on earth, the rediscovered Pompeii gives us access to the ancient world. And now, with new findings and new insights, we can tell the story of the ordinary people caught up in this disaster. These are the forgotten men and women who lived when Rome ruled....and were buried when the volcano blew.

For centuries, Rome governed hundreds of thousands of people in an empire that covered as much as 2 million square miles. In an age when most travel was done on foot, how was this possible? Digging deep into the lives of two emperors who presided over one of the most successful periods in Roman history, NGC explores how the empire owed its longevity to its ambition, innovation and genius for administration. See how Rome endured for centuries as one of the greatest bureaucracies on earth.

Find out how Julius Caesar created one of the most powerful positions in the Roman Empire using business backing, the armed forces and religion to sway elections and politicians. Eventually, the man was so powerful that the only way to stop him was through assassination. On the eve of the 2055th anniversary of Caesar’s death, 15th March, this documentary explores how the Roman Empire had balanced the aims of great men with the shared power of a Republic for four centuries before Julius Caesar used all the instruments of state against the state itself in a bid for the biggest job in the Roman world.