In the Memoirs and in this guide, the term “Rome” refers both to the city located in central Italy and the empire of which it was the capital. “Rome” is also used to refer to the broader civilization whose philosophy, art and architecture, and enduring infrastructure had a foundational impact on the Western world.

The beginnings of Rome are traditionally dated to 753 BCE and the reign of its first king. The Senate emerged as a governing body made up of men from the influential and propertied families of the realm. The founding of the Roman Republic dates to 509 BCE, when the last Roman king was overthrown. In the Republic, control of the judicial system and the military was put in the hands of elected magistrates called consuls; customarily, there were two to three consuls ruling at once. The Roman state conquered southern Europe and northern Africa in the Third Punic War (149-146 BCE). Roman territory also expanded eastward with the conquest of Macedonia and the absorption of the Greek kingdoms.

In the first century BCE, the consuls became military dictators, with the influential Julius Caesar becoming consul for life upon the end of a civil war. Concerns that he would bring about an end of the Republic led to Caesar’s assassination in 44 BCE. During the next regime, Caesar’s great-nephew and adopted heir, Octavian, fought with his co-consul Mark Antony, who was supported by Cleopatra, the ruler of Egypt. Octavian defeated Antony and Cleopatra’s forces in the Battle of Actium in 31 BCE, leaving him the sole ruler of Rome. While he retained the Senate and other governing institutions of the Republic, Octavian took the title of Augustus in 27 BCE, becoming the first Emperor of Rome.

The relative stability that Augustus imposed on the empire, along with the civil reforms and building projects he undertook, introduced a time of prosperity known as the Pax Romana, or the Roman Peace. This period is generally agreed to have endured until 180 CE, and Augustus is credited with increasing the reach of Roman culture as well as military dominance. While the Senate endured as a body, continuing to be made up of propertied and influential men from important families, Augustus assumed more and more executive power. The popularity and admiration Augustus gained as a result of his reforms and the comparative stability of his reign led the Senate to deify him at his death. Worship of Augustus became part of the state religion of Rome, which was an assemblage of cults, rituals, and practices that served more to unite the populace in upholding Roman values than inspiring spiritual guidance.

Successors to Augustus included the unpopular Tiberius (r. 14-37 CE); Caligula (r. 37-41 CE), who became infamous for his cruelty; Claudius (r. 41-54 CE), who was well-educated but viewed as physically weak; and Nero (r. 54-68 CE), who was blamed for the fire that devasted the city of Rome in 64. After a civil war following the death of Nero, Vespasian emerged as sole emperor (r. 69-79 CE), and was succeeded by his sons Titus (r. 79-81 CE) and Domitian (r. 81-96 CE). Domitian proved controversial and unpopular as a ruler; after his assassination, the Senate declared Nerva emperor, beginning the succession outlined in the Memoirs and the dynasty often called the Five Good Emperors. Trajan succeeded Nerva in 98 CE, Hadrian succeeded Trajan in 117 CE, and Antoninus Pius succeeded Hadrian in 138 CE. Hadrian had arranged for Antoninus to adopt Hadrian’s preferred successors; after Antoninus died of natural causes at age 74 in 161 CE, his adopted sons, Marcus Aurelius and Lucius Verus, became co-emperors. Lucius Verus died in 169 CE.

Marcus Aurelius broke with tradition to make his son Commodus co-ruler in 177 CE, but after Marcus’s death in 180 CE, Commodus proved a less capable ruler than his predecessors, more interested in personal glory than administration. His assassination in 192 CE led to another period of civil war; following that, instability within the empire and external pressure of non-Roman tribes brought the fabled Pax Romana to an end. Diocletian split the empire into two halves in 293 CE, with the Western half ruled by an emperor based in Rome and the Eastern half ruled from Constantinople.

In the fifth century, due to attacks from the barbarian tribes Hadrian foresees in the Memoirs, the Western empire gradually lost territory. In 476 CE, the defeat of Romulus Augustus by the Germanic ruler Odoacer brought the Western Roman Empire to an end, and former Roman provinces evolved into independent nations and territories. The Eastern Empire, also known as the Byzantine Empire, endured for another 1,000 years, only ending with the conquest of Constantinople by the leader of the Ottoman Army in 1453, whereupon the territories became part of the Ottoman Empire.