What significant event occurred in the formation of the Roman Empire in 27 BC?

The significant event in the formation of the Roman Empire in 27 BC was the rise of Augustus as the first emperor. This marked the transition from the Roman Republic to the Roman Empire, which fundamentally altered the structure and governance of Rome. Augustus, originally known as Octavian, was the adopted heir of Julius Caesar and emerged victorious after a series of civil wars. His ascension to power paved the way for an imperial system that provided stability after years of conflict.

This event also established the precedent for the imperial rule that would shape Roman governance for centuries to come, as Augustus held ultimate authority over military, political, and social aspects of Roman life, thus centralizing power. His reign is often seen as the beginning of the Pax Romana, a long period of relative peace and prosperity within the empire, further solidifying his crucial role in shaping Roman history.

In contrast, while the establishment of the Senate was essential to the earlier structure of the Republic and the division of the empire occurred much later (in 285 AD under Diocletian), the construction of the Colosseum, which began in AD 72, was significant but not related to the formation of the empire in 27 BC. These events represent different facets of Roman history