The Roman Empire: A Complete History from Founding to Fall

Few civilizations in human history have left a mark as deep and as enduring as Rome. From a cluster of huts on the Palatine Hill to a state that ruled the entire Mediterranean basin, the story of Rome is the story of how a small Latin settlement came to define law, language, engineering, and political thought for more than two millennia. The history of the Roman Empire is not just the chronicle of one people. It is the foundation upon which Western civilization, the Christian Church, the concept of citizenship, and the very idea of Europe were built.

This article is a comprehensive overview. It traces the arc from the mythical founding of the city by Romulus and Remus through the Roman Republic, the conquests that built an empire, the long peace of the Pax Romana, the crisis of the third century, the Christian revolution under Constantine the Great, and finally the fall of the Western Roman Empire in 476 CE. Along the way, it points to deeper articles on each major era, each major figure, and each pivotal battle.

The Origins: Myth and Archaeology

Roman tradition, recorded most famously by Virgil in the Aeneid and by Livy in his history of the city, held that Rome was founded on 21 April 753 BCE by Romulus, the son of Mars and the Vestal Virgin Rhea Silvia. Romulus and his twin brother Remus, descendants of the Trojan hero Aeneas, were suckled by a she-wolf before founding the city. Romulus killed Remus and gave the city his name.

Modern archaeology tells a more complicated story. The earliest settlements on the Roman Forum and the Palatine date to roughly the 10th century BCE, with huts built on stilts above marshy ground. By the 8th century BCE these villages had grown into a loose federation of hilltop communities, and by the 6th century BCE they had been unified into a single city under the rule of Etruscan kings. The historical truth behind Rome’s origin story is therefore not a single act of foundation but a slow process of consolidation.

The last of the semi-legendary kings, Tarquinius Superbus, was overthrown around 509 BCE, an event the Romans considered the birth of their Republic. Whether the revolution was a popular uprising, an aristocratic coup, or a foreign invasion remains debated, but its consequences were revolutionary: power would henceforth be exercised not by kings but by elected magistrates, advised by a senate and constrained by written law.

The Roman Republic: A Century of Conquest

The Roman Republic was not, in its first centuries, a democracy. It was an oligarchy in which a small class of patrician families dominated the Roman Senate and the senior magistracies. The plebeians, the common people, fought a long political battle for access to office and to legal protections, eventually winning the codification of the laws in the Twelve Tables around 450 BCE and the right to hold the consulship in 366 BCE.

What transformed Rome from a city-state into an imperial power was the series of wars fought against Carthage, the great Phoenician colony of North Africa. The Punic Wars, fought across the Mediterranean between 264 and 146 BCE, were among the most brutal and consequential conflicts of the ancient world. In the first war Rome won Sicily, Sardinia, and Corsica. In the second, after Hannibal crossed the Alps with his elephants and annihilated Roman armies at Lake Trasimene and Cannae, Rome ultimately prevailed. The third war ended with the complete destruction of Carthage in 146 BCE. By the time of the final victory over Carthage, Rome was the unrivalled master of the western Mediterranean.

The same generation that destroyed Carthage also destroyed Corinth, the great Greek city, and incorporated Greece into the Roman sphere. Within a single lifetime Rome had become a Mediterranean empire.

The Late Republic and the Crisis of Liberty

Wealth from conquest changed Roman society. Vast estates worked by slaves captured in war displaced small farmers, who migrated to the city and formed an urban underclass dependent on subsidized grain. Generals who had led armies across the Mediterranean became too powerful to be controlled by the Senate. Tiberius Gracchus, who tried to redistribute public land to the poor, was murdered in 133 BCE along with 300 of his supporters. A century of political violence began.

The fall of the Roman Republic was a slow process punctuated by civil wars. Gaius Marius reformed the army, allowing landless citizens to enlist, and thereby bound the loyalty of soldiers to their commanders rather than to the state. Sulla marched on Rome itself in 88 BCE and held a proscription in which hundreds of citizens were killed for their property. Pompey, Crassus, and Julius Caesar formed the First Triumvirate, an informal alliance that bypassed senatorial authority. Caesar crossed the Rubicon in 49 BCE, chased Pompey across the Mediterranean, and returned to Rome as perpetual dictator. He was assassinated on the Ides of March, 44 BCE.

A new round of civil wars followed Caesar’s death, ending only when Caesar’s adopted son Octavian defeated Mark Antony and Cleopatra at the Battle of Actium in 31 BCE. Octavian, now styled Augustus, became the first emperor in 27 BCE. The Republic had ended; the Empire had begun.

The Principate: Augustus and the Pax Romana

The reign of Augustus Caesar, from 27 BCE to 14 CE, marked one of the great turning points in Western history. Augustus was careful to preserve the forms of the Republic. The Senate continued to meet, magistrates continued to be elected, and the language of republican liberty was maintained. In reality, however, all real power was concentrated in the hands of the princeps, the “first citizen,” who held a bundle of overlapping offices and commanded every legion.

The century that followed Augustus’s reign is sometimes called the Pax Romana, the Roman Peace. It was a period in which the borders of the empire stabilized, the economy flourished, trade expanded, and the Mediterranean became, for the first time, a single unified market. Goods from Roman Britain traveled to Roman Egypt, and grain from Egypt fed the million inhabitants of Rome.

The Julio-Claudian dynasty ruled for almost a century after Augustus, ending with the suicide of Nero in 68 CE. The Flavian dynasty that followed began the Colosseum and pushed the empire to its greatest territorial extent by completing the conquest of Britain.

The Five Good Emperors of the second century — Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius — are often considered the high point of the imperial system. Trajan conquered Dacia (modern Romania) and reached the Persian Gulf, the farthest east Rome would ever push. Hadrian consolidated the empire behind fixed frontiers, most famously Hadrian’s Wall in northern Britain. Marcus Aurelius, the philosopher-emperor, spent most of his reign on the Danube fighting Germanic invasions.

The Crisis of the Third Century

The death of Marcus Aurelius in 180 CE marked the end of the Antonine age. His son Commodus, portrayed unforgettably by Joaquin Phoenix in the film Gladiator, was assassinated in 192 CE, and the empire plunged into a half-century of catastrophe known as the Crisis of the Third Century.

Between 235 and 284 CE, the empire saw at least 26 emperors, most of whom died violently. The Roman army became the kingmaker, raising and deposing emperors in rapid succession. Persia under the Sassanid dynasty pushed Rome out of Mesopotamia. Germanic tribes crossed the Rhine and the Danube. The Plague of Cyprian, possibly smallpox or a viral hemorrhagic fever, killed perhaps five million people. Inflation spiraled as the silver content of the denarius collapsed to almost nothing.

The crisis ended only with the accession of Diocletian in 284 CE. Diocletian restored the empire’s finances, doubled the size of the army, and instituted the Tetrarchy, a system of four co-emperors intended to provide stable succession and to defend the vast frontiers.

The Christian Revolution and the Later Empire

The most consequential religious change in Roman history occurred under Constantine the Great. In 313 CE, Constantine and his co-emperor Licinius issued the Edict of Milan, granting legal tolerance to Christianity throughout the empire. In 325 CE, Constantine convened the Council of Nicaea, producing the Nicene Creed, the foundational statement of Christian orthodoxy. In 330 CE, he moved the capital of the empire from Rome to the old Greek colony of Byzantium, which he renamed Constantinople.

Christianity, once a persecuted Jewish sect, became the official religion of the empire within a single generation. The transformation was profound. Roman temples fell into ruin or were converted into churches. The Vestal Virgins lost their state funding. Christian bishops became powerful political figures. Latin ceased to be the universal language of the eastern provinces, where Greek remained dominant.

The fifth century was a slow catastrophe. The Visigoths sacked Rome in 410 CE under Alaric, an event that shocked the Mediterranean world. The Vandals sacked it again in 455 CE. In 476 CE, the Germanic chieftain Odoacer deposed the last western emperor, Romulus Augustulus, and sent the imperial regalia to Constantinople. The Western Roman Empire had ended.

The Survival of the East

The story did not end in 476. The Eastern Roman Empire, ruled from Constantinople, survived for almost another thousand years. Modern historians call it the Byzantine Empire, although its citizens always called themselves Romans. Under Justinian in the sixth century, Byzantine armies reconquered Italy, North Africa, and southern Spain. The Hagia Sophia, the greatest church of the Christian East, was completed in 537 CE.

Constantinople fell to the Ottoman Turks in 1453, and the last Roman emperor, Constantine XI, died fighting on the walls. With him, the Roman state, in one form or another, had lasted for 2,204 years from the legendary foundation by Romulus.

The Roman Legacy

The Romans left a legacy so pervasive that it is often invisible. The modern Romance languages — Italian, French, Spanish, Portuguese, Romanian — are direct descendants of the Latin language. The Roman legal tradition underlies the civil law systems of continental Europe, Latin America, and much of Africa and Asia. The Catholic Church, headquartered in Rome, adopted the Roman administrative model for its own dioceses and parishes. Republican political theory, from Machiavelli to the American Founding Fathers, drew heavily on Roman precedents.

Roman engineering survives in the physical fabric of Europe. Roman roads still form the basis of European highways. Roman aqueducts still carry water in Segovia and other cities. Roman concrete, the secret of which was only recently rediscovered, has lasted two thousand years underwater. The arch, the dome, the basilica, the triumphal arch — all are Roman inventions still in everyday use.

To understand Rome is to understand the deep grammar of Western civilization. The next articles in this series explore each of these themes in depth.

The Roman Army at Its Height

The single greatest instrument by which Rome built and held its empire was the Roman legion. Under the early Empire, the army was a professional long-service force, with legionaries enlisted for twenty-five years and auxiliaries for similar terms. By the reign of Hadrian, the empire fielded about 30 legions, roughly 150,000 heavy infantry, supported by an approximately equal number of auxiliary infantry and cavalry. Counting the fleet, the Praetorian Guard, the urban cohorts, and the vigiles, the total military establishment may have approached half a million men.

The army was not merely a fighting force. It was the principal agent of Romanization, the process by which conquered peoples became Roman. A legion stationed at Chester or Mainz or Dura-Europos for two decades built roads, bridges, and aqueducts, intermarried with local women, and retired on land grants in the surrounding colony. By the early third century CE, the army was overwhelmingly recruited from the provinces, and the emperor Septimius Severus, himself an African, could dismiss the Roman legionaries of the Praetorian Guard and replace them with his own Danubian troops without anyone thinking the gesture strange.

The empire’s military frontiers were not continuous walls but zones of depth. The Rhine, the Danube, the Euphrates, and the Atlas Mountains served as natural barriers, behind which stood a network of forts, towers, and roads. In Britain, Hadrian’s Wall ran 73 miles from the Tyne to the Solway, garrisoned by auxiliary cohorts. In the east, the legions of Syria watched the Parthian and later Sassanid frontier for almost five centuries. The system was enormously expensive, but it was also extraordinarily durable. For two hundred years, from the accession of Augustus to the death of Marcus Aurelius, no serious invasion of the Roman heartland ever succeeded.

The Provinces and Romanization

By the second century CE, the Roman Empire contained perhaps fifty provinces, stretching from Roman Britain in the northwest to Roman Egypt in the southeast, and from the Atlantic coast of Roman Gaul to the Syrian desert. Each province was governed by an imperial legate of senatorial or equestrian rank, supported by a substantial staff of Roman officials. Justice was administered in the Roman manner. Taxes were collected in Roman coin. Roads and cities were built on the Roman plan.

The most profound transformation the provinces underwent was cultural. Latin spread as the language of administration, the army, and the cities, while Greek remained dominant in the eastern Mediterranean, where it had been the lingua franca since the conquests of Alexander. Local gods were identified with Roman gods: the Celtic Lugus became Mercury, the Brittonic Sulis became Minerva, the Egyptian Isis became a universally worshipped deity whose temples stood in every Roman city. The result was a hybrid Greco-Roman culture, uniform enough to hold the empire together, varied enough to absorb new peoples.

By the second century, the provincial aristocracies had become thoroughly Romanized. Senators from Gaul, Spain, North Africa, and even Mauretania sat in the Roman Senate, commanded legions, and held the consulship. The emperor Trajan came from Italica in Spain. Hadrian came from the same town. Septimius Severus came from Lepcis Magna in Africa. The provincialization of the imperial ruling class is one of the great success stories of the Roman project: the empire had transformed conquered peoples into Romans, and they in turn had begun to govern it.

The cities of the provinces were the visible evidence of this transformation. Every provincial capital had a forum, a basilica, a temple, a theater or amphitheater, public baths, an aqueduct, and paved streets. Cities like Lyon, Tarragona, Carthage, Antioch, and Ephesus were as fully Roman as Rome itself. When archaeologists dig at these sites today, they find inscriptions in Latin, statues in the Roman style, and houses built on the Roman plan. The process was not entirely peaceful. Resistance was real and often violent, from the Jewish revolts of 66 and 132 CE to the long guerrilla war in the山区 of Asturias in northern Spain. But the long-term result was the creation of a shared Mediterranean civilization that would outlast the empire itself.

Trade, Coinage, and the Roman Economy

The economy of the high Empire was the most integrated the ancient world would ever see. The Mediterranean, the Romans liked to say, was a single Roman lake, the Mare Nostrum. Goods moved freely, and a single currency, the silver denarius and later the gold aureus, circulated from the Atlantic to the Euphrates. The supply was guaranteed by the imperial mints of Rome, Lyon, and Antioch, and the purity of the coinage was maintained, with minor exceptions, for almost three centuries.

The trade was astonishing in scale. Grain from Roman Egypt and North Africa fed the million inhabitants of Rome. Olive oil from Baetica, in southern Spain, has been found in Roman forts as far away as northern Britain. Wine from Italy, Gaul, and the Aegean was exported to every province. Spices, silk, and precious stones came overland from India and China, via the caravan routes through Palmyra and Petra. Slaves, an important commodity, were traded in every major port.

The size of this trade can be measured in archaeology. The Monte Testaccio in Rome is an artificial hill 35 meters high and more than a kilometer in circumference, made entirely of broken amphorae, the ceramic jars in which olive oil was imported from Baetica in the first three centuries CE. The volume of oil it represents, perhaps 6 billion liters, is a striking testimony to the scale of Roman commerce.

The economy was not, however, a modern market economy. It was a slave-based, agrarian system in which the great estates of the wealthy produced most of the surplus, and most ordinary citizens lived close to subsistence. The imperial government extracted taxes in coin, but most economic activity remained local. The great long-distance trades in grain, oil, wine, metals, and luxury goods were a thin layer over a vast base of peasant agriculture. When this trade network began to break down in the third century, the result was the catastrophic inflation and social dislocation of the crisis of the third century. For a fuller discussion of Roman military organization, see the Roman legion.

Law, Citizenship, and the Roman Idea of Government

One of the deepest contributions of Rome to Western civilization was its concept of law and citizenship. Roman law, codified in the Twelve Tables around 450 BCE and elaborated by centuries of juristic writing, distinguished between the ius civile, the law applying to Roman citizens, and the ius gentium, the law of peoples, applicable to all subjects of the empire. The Corpus Juris Civilis, the great sixth-century codification of Roman law, became the foundation of the civil law tradition that still governs most of continental Europe, Latin America, and large parts of Africa and Asia.

The idea of Roman citizenship was equally transformative. In the early Republic, citizenship was a narrow privilege, restricted to freeborn males of the Italian city-states that had been incorporated into the Roman alliance. Over time, the Romans extended citizenship to their Italian allies after the Social War of 91–88 BCE, to provincial communities as a reward for loyalty, and finally, in 212 CE, the emperor Caracalla granted citizenship to every free inhabitant of the empire. The result was the first large-scale political community in which the great majority of free residents enjoyed a common legal status, with the right to marry Roman citizens, to own Roman property, and to appeal Roman courts.

The emperor and the Roman Senate were the principal organs of government. The Senate, originally an advisory body of ex-magistrates, became, in the imperial period, a hereditary council of the great aristocratic families, still influential in the administration of the provinces, in the management of the state religion, and in the formal recognition of new emperors. The Senate continued to meet in the Curia in the Roman Forum until the seventh century, long after the Western Empire itself had fallen. The combination of written law, elected magistrates, and a deliberative senate, the res publica, was the political model that the founders of the American republic consciously imitated in the eighteenth century, and that almost every modern parliamentary system still echoes.