the roman empire reached its greatest extent during the
Roman Empire The Roman Empire (Latin: Imperium Rōmānum, Classical Latin: [ɪmˈpɛ.ri.ũː roːˈmaː.nũː]; Koine and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr. Basileia tōn Rhōmaiōn) was the post-Roman Republic period of the ancient Roman civilization, characterized by government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome was the largest city in the world c. 100 BC – c. AD 400, with Constantinople (New Rome) becoming the largest around AD 500,[5][6] and the Empire's populace grew to an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time).[n 7][7] The 500-year-old republic which preceded it was severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt. Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title Augustus, effectively marking the end of the Roman Republic.
1st century During this period, Europe, North Africa and the Near East fell under increasing domination by the Roman Empire, which continued expanding, most notably conquering Britain under the emperor Claudius (AD 43). The reforms introduced by Augustus during his long reign stabilized the empire after the turmoil of the previous century's civil wars. Later in the century the Julio-Claudian dynasty, which had been founded by Augustus, came to an end with the suicide of Nero in AD 68. There followed the famous Year of Four Emperors, a brief period of civil war and instability, which was finally brought to an end by Vespasian, ninth Roman emperor, and founder of the Flavian dynasty. The Roman Empire generally experienced a period of prosperity and dominance in this period and the First Century is remembered as part of the Empire's golden age.