Part 2/14:
31 BC and the Battle of Actium mark the end of the Roman Republic, leading to Octavian’s rise as Augustus and the beginning of imperial rule. Some see this as the start of Rome’s decline.
Many point to AD 180, the death of Emperor Marcus Aurelius, as the decline's symbolic turning point. This date is popular in Hollywood, featured notably in the film Gladiator and the classic The Fall of the Roman Empire. Cassius Dio, an ancient historian, famously lamented Rome's transition from "a kingdom of gold to one of iron and rust."
The early 4th century AD, especially AD 312, marks the rise of Constantine and the official adoption of Christianity, which some argue conflicted with traditional Roman values.
The barbarian invasions, especially: