Question: Who was the first Emperor of the city that was the center of imperial life in the empire that inspired the Carolingian Empire?

<P0-S0> the imperial period of rome lasted approximately 1,500 years compared to the 500 years of the republican era. <P0-S1> the first two centuries of the empire's existence were a period of unprecedented political stability and prosperity known as the pax romana, or ``roman peace ''. <P0-S2> following octavian's victory, the size of the empire was dramatically increased. <P0-S3> after the assassination of caligula in ad 41, the senate briefly considered restoring the republic, but the praetorian guard proclaimed claudius emperor instead. <P0-S4> under claudius, the empire invaded britannia, its first major expansion since augustus. <P0-S5> after claudius' successor, nero, committed suicide in ad 68, the empire suffered a series of brief civil wars, as well as a concurrent major rebellion in judea, during which four different legionary generals were proclaimed emperor. <P0-S6> vespasian emerged triumphant in ad 69, establishing the flavian dynasty, before being succeeded by his son titus, who opened the colosseum shortly after the eruption of mount vesuvius. <P0-S7> his short reign was followed by the long reign of his brother domitian, who was eventually assassinated. <P0-S8> the senate then appointed the first of the five good emperors. <P0-S9> the empire reached its greatest extent under trajan, the second in this line. <SEP> <P1-S0> charlemagne (/ ˈʃɑːrlɪmeɪn /) or charles the great (2 april 742 -- 28 january 814), numbered charles i, was king of the franks from 768, king of the lombards from 774 and emperor of the romans from 800. he united much of europe during the early middle ages. <P1-S1> he was the first recognised emperor in western europe since the fall of the western roman empire three centuries earlier. <P1-S2> the expanded frankish state that charlemagne founded is called the carolingian empire. <SEP> <P2-S0> Under Charlemagne the Franks reached the height of their power. <P2-S1> After campaigns against Lombards, Avars, Saxons, and Basques, the resulting Carolingian Empire stretched from the Pyrenees to Central Germany, from the North Sea to the Adriatic. <P2-S2> In 800 the Pope made Charlemagne Emperor of the West in return for protection of the Church. <P2-S3> The Carolingian Empire was a conscious effort to recreate a central administration modeled on that of the Roman Empire,[13] but the motivations behind military expansion differed. <P2-S4> Charlemagne hoped to provide his nobles an incentive to fight by encouraging looting on campaign. <P2-S5> Plunder and spoils of war were stronger temptations than imperial expansion, and several regions were invaded over and over in order to bolster the coffers of Frankish nobility. <P2-S6> [14] Cavalry dominated the battlefields, and while the high costs associated with equipping horses and horse-riders helped limit their numbers, Carolingian armies maintained an average size of 20,000 by recruiting infantry from imperial territories near theaters of operation. <P2-S7> [15] The Empire lasted from 800 to 843, when, following Frankish tradition, it was split between the sons of Louis the Pious by the Treaty of Verdun. <SEP> <P3-S0> For almost a thousand years, Rome was the most politically important, richest and largest city in Europe. <P3-S1> Around 100 CE, it had a population of about 450,000, and declined to a mere 20,000 during the Early Middle Ages, reducing the sprawling city to groups of inhabited buildings interspersed among large areas of ruins and vegetation. <SEP> <P4-S0> However, civil war flared again when the Second Triumvirate of Octavian, Lepidus and Mark Antony failed. <P4-S1> The ambitious Octavian built a power base of patronage and then launched a campaign against Mark Antony. <P4-S2> At the naval Battle of Actium off the coast of Greece, Octavian decisively defeated Antony and Cleopatra. <P4-S3> Octavian was granted a series of special powers including sole "imperium" within the city of Rome, permanent consular powers and credit for every Roman military victory, since all future generals were assumed to be acting under his command. <P4-S4> In 27 BC Octavian was granted the use of the names "Augustus" and "Princeps", indicating his primary status above all other Romans, and he adopted the title "Imperator Caesar" making him the first Roman Emperor.