In 27 BC, the Senate made Octavian imperator ("commander") thus beginning the Principate, the first epoch of Roman imperial history usually dated from 27 BC to AD 284; later that year they awarded him the name Augustus, "the venerated". Subsequent emperors all took this name as the imperial title Augustus.

The Roman Empire began in 27 BCE when Augustus became the sole ruler of Rome. Augustus and his successors tried to maintain the imagery and language of the Roman Republic to justify and preserve their personal power. Beginning with Augustus, emperors built far more monumental structures, which transformed the city of Rome.

In 27 BC, Caesar Augustus officially became the first Roman Emperor after defeating Mark Antony and Cleopatra at the Battle of Actium. This event marked the end of the Roman Republic and the beginning of the Roman Empire. Augustus’ reign was characterized by a period of peace and prosperity known as the Pax Romana.