Imperium Romanum (Pax Romana in the original) is the third campaign that was introduced in Age of Empires: The Rise of Rome. The player controls the Romans after the reign of Caesar, defending the Roman Empire from its enemies.
- The Battle of Actium (named Actium in the original)
- Year of the Four Emperors (reworked version of the original)
- Ransom at Ctesiphon (named Ctesiphon in the original)
- Zenobia, Queen of Palmyra (named Queen Zenobia in the original)
- Coming of the Huns (reworked version of the original)