When master builder Haterius constructs the Colosseum from the ashes of Nero's Golden House, his work is far from over. New Emperor Domitian tasks him with adding in a complex network of underground tunnels: the hypogeum. Haterius will have to balance satisfying the insatiable demands of the all-powerful Emperor, with the extreme pressures of creating an ancient architectural marvel in time for Domitian's games. Failure could cost his life.

As the Roman Empire continues to expand, so does the diversity of exotic beasts brought back to entertain the Colosseum crowds. Over a million animals are slaughtered on the sands of the arena by trained beast masters, none more famous than Carpophorus. But when met with the unprecedented challenge to battle 20 wild creatures, can Carpophorus survive?

When the mighty Emperor Trajan throws his great games of 107 AD, the crowd is treated to a rare spectacle: female gladiators. The combatants are typically prisoners of war, but in one game, a Roman woman named Mevia makes history. She decides to trade her status as a free citizen of Rome to fight in the arena as a gladiatrix, a controversial and shocking choice that earns the enmity of Roman historian and satirist, Juvenal. Her choice illustrates the challenges of plebian life for women in ancient Rome.

The public execution of criminals is a staple in the Colosseum, but during Trajan's 123 days of games in 107 AD, one of these victims is no ordinary prisoner. Bishop Ignatius of Antioch is part of a growing underground religion threatening Roman traditions: Christianity. Will his high-profile execution send a message, or spread the word of Christ further than Trajan could have anticipated?

One of the most famous doctor/scientists of the ancient world, Galen of Pergamon makes a name for himself as a physician for gladiators in the arena. But just as Rome's Empire reaches the height of its power and influence under Emperor Marcus Aurelius, a devastating plague sweeps through the city--and Galen catches the attention of Emperor Marcus Aurelius. Now it's up to this scientist to defend Rome from disease and keep the Emperor alive at all costs. This episode marks a turning point in the series, as barbarian attacks along Rome's northern borders intensify, beginning the long period of Rome's decline.

All of Rome’s emperors have put great value on spectacles and games, but only one steps out of the Imperial Box and onto the sands of the arena: Commodus. A far cry from his father, the great Emperor Marcus Aurelius, Commodus is quick to make enemies - especially with one elite ruling body, the Senate. As the empire crumbles and Commodus’s popularity plummets, a deadly game of cat and mouse ensues, centered around Rome’s great amphitheater.

By the 4th Century AD, a divided Roman Empire is rocked by devastating earthquakes, fires, barbarian invasions and deep religious divides. As Rome declines, the Colosseum, which once stood as a proud symbol of the Empire’s glory, lies empty. To restore Rome, one man, a devout worshipper of the Rome's old Gods, turns to the arena. Can staging elaborate and expensive games there reverse Rome’s decline?