Beginning in the eighth century B.C., Ancient Rome grew from a small town on central Italy’s Tiber River into an empire that at its peak encompassed most of continental Europe, Britain, much of western Asia, northern Africa and the Mediterranean islands. Among the many legacies of Roman dominance are the widespread use of the Romance languages (Italian, French, Spanish, Portuguese and Romanian) derived from Latin, the modern Western alphabet and calendar and the emergence of Christianity as a major world religion.

After 450 years as a republic, Rome became an empire in the wake of Julius Caesar’s rise and fall in the first century B.C. The long and triumphant reign of its first emperor, Augustus, began a golden age of peace and prosperity; by contrast, the Roman Empire’s decline and fall by the fifth century A.D. was one of the most dramatic implosions in the history of human civilization.

Origins of Rome

As legend has it, Rome was founded in 753 B.C. by Romulus and Remus, twin sons of Mars, the god of war. Left to drown in a basket on the Tiber by a king of nearby Alba Longa and rescued by a she-wolf, the twins lived to defeat that king and found their own city on the river’s banks in 753 B.C. After killing his brother, Romulus became the first king of Rome, which is named for him.

A line of Sabine, Latin and Etruscan (earlier Italian civilizations) kings followed in a non-hereditary succession. There are seven legendary kings of Rome: Romulus, Numa Pompilius, Tullus Hostilius, Ancus Martius, Lucius Tarquinius Priscus (Tarquin the Elder), Servius Tullius and Tarquinius Superbus, or Tarquin the Proud (534-510 B.C.). While they were referred to as “Rex,” or “King” in Latin, all the kings after Romulus were elected by the senate.

Did you know? Four decades after Constantine made Christianity Rome's official religion, Emperor Julian—known as the Apostate—tried to revive the pagan cults and temples of the past, but the process was reversed after his death, and Julian was the last pagan emperor of Rome.

Rome’s era as a monarchy ended in 509 B.C. with the overthrow of its seventh king, Lucius Tarquinius Superbus, whom ancient historians portrayed as cruel and tyrannical, compared to his benevolent predecessors. A popular uprising was said to have arisen over the rape of a virtuous noblewoman, Lucretia, by the king’s son. Whatever the cause, Rome turned from a monarchy into a republic, a world derived from res publica, or “property of the people.”

Rome was built on seven hills, known as “the seven hills of Rome”—Esquiline Hill, Palatine Hill, Aventine Hill, Capitoline Hill, Quirinal Hill, Viminal Hill and Caelian Hill. 

The Early Republic

The power of the monarch passed to two annually elected magistrates called consuls. They also served as commanders in chief of the army. The magistrates, though elected by the people, were drawn largely from the Senate, which was dominated by the patricians, or the descendants of the original senators from the time of Romulus. Politics in the early republic was marked by the long struggle between patricians and plebeians (the common people), who eventually attained some political power through years of concessions from patricians, including their own political bodies, the tribunes, which could initiate or veto legislation.

In 450 B.C., the first Roman law code was inscribed on 12 bronze tablets–known as the Twelve Tables–and publicly displayed in the Roman Forum. These laws included issues of legal procedure, civil rights and property rights and provided the basis for all future Roman civil law. By around 300 B.C., real political power in Rome was centered in the Senate, which at the time included only members of patrician and wealthy plebeian families.

Military Expansion

During the early republic, the Roman state grew exponentially in both size and power. Though the Gauls sacked and burned Rome in 390 B.C., the Romans rebounded under the leadership of the military hero Camillus, eventually gaining control of the entire Italian peninsula by 264 B.C. Rome then fought a series of wars known as the Punic Wars with Carthage, a powerful city-state in northern Africa.

The first two Punic Wars ended with Rome in full control of Sicily, the western Mediterranean and much of Spain. In the Third Punic War (149–146 B.C.), the Romans captured and destroyed the city of Carthage and sold its surviving inhabitants into slavery, making a section of northern Africa a Roman province. At the same time, Rome also spread its influence east, defeating King Philip V of Macedonia in the Macedonian Wars and turning his kingdom into another Roman province.

Rome’s military conquests led directly to its cultural growth as a society, as the Romans benefited greatly from contact with such advanced cultures as the Greeks. The first Roman literature appeared around 240 B.C., with translations of Greek classics into Latin; Romans would eventually adopt much of Greek art, philosophy and religion.

Internal Struggles in the Late Republic

Rome’s complex political institutions began to crumble under the weight of the growing empire, ushering in an era of internal turmoil and violence. The gap between rich and poor widened as wealthy landowners drove small farmers from public land, while access to government was increasingly limited to the more privileged classes. Attempts to address these social problems, such as the reform movements of Tiberius and Gaius Gracchus (in 133 B.C. and 123-22 B.C., respectively) ended in the reformers’ deaths at the hands of their opponents.

Gaius Marius, a commoner whose military prowess elevated him to the position of consul (for the first of six terms) in 107 B.C., was the first of a series of warlords who would dominate Rome during the late republic. By 91 B.C., Marius was struggling against attacks by his opponents, including his fellow general Sulla, who emerged as military dictator around 82 B.C. After Sulla retired, one of his former supporters, Pompey, briefly served as consul before waging successful military campaigns against pirates in the Mediterranean and the forces of Mithridates in Asia. During this same period, Marcus Tullius Cicero, elected consul in 63 B.C., famously defeated the conspiracy of the patrician Cataline and won a reputation as one of Rome’s greatest orators.

Julius Caesar’s Rise

When the victorious Pompey returned to Rome, he formed an uneasy alliance known as the First Triumvirate with the wealthy Marcus Licinius Crassus (who suppressed a slave rebellion led by Spartacus in 71 B.C.) and another rising star in Roman politics: Gaius Julius Caesar. After earning military glory in Spain, Caesar returned to Rome to vie for the consulship in 59 B.C. From his alliance with Pompey and Crassus, Caesar received the governorship of three wealthy provinces in Gaul beginning in 58 B.C.; he then set about conquering the rest of the region for Rome.

After Pompey’s wife Julia (Caesar’s daughter) died in 54 B.C. and Crassus was killed in battle against Parthia (present-day Iran) the following year, the triumvirate was broken. With old-style Roman politics in disorder, Pompey stepped in as sole consul in 53 B.C. Caesar’s military glory in Gaul and his increasing wealth had eclipsed Pompey’s, and the latter teamed with his Senate allies to steadily undermine Caesar. In 49 B.C., Caesar and one of his legions crossed the Rubicon, a river on the border between Italy from Cisalpine Gaul. Caesar’s invasion of Italy ignited a civil war from which he emerged as dictator of Rome for life in 45 B.C.

From Caesar to Augustus

Less than a year later, Julius Caesar was murdered on the ides of March (March 15, 44 B.C.) by a group of his enemies (led by the republican nobles Marcus Junius Brutus and Gaius Cassius). Consul Mark Antony and Caesar’s great-nephew and adopted heir, Octavian, joined forces to crush Brutus and Cassius and divided power in Rome with ex-consul Lepidus in what was known as the Second Triumvirate. With Octavian leading the western provinces, Antony the east, and Lepidus Africa, tensions developed by 36 B.C. and the triumvirate soon dissolved. In 31 B.C., Octavian triumped over the forces of Antony and Queen Cleopatra of Egypt (also rumored to be the onetime lover of Julius Caesar) in the Battle of Actium. In the wake of this devastating defeat, Antony and Cleopatra committed suicide.

By 29 B.C., Octavian was the sole leader of Rome and all its provinces. To avoid meeting Caesar’s fate, he made sure to make his position as absolute ruler acceptable to the public by apparently restoring the political institutions of the Roman republic while in reality retaining all real power for himself. In 27 B.C., Octavian assumed the title of Augustus, becoming the first emperor of Rome.

Age of the Roman Emperors

Augustus’ rule restored morale in Rome after a century of discord and corruption and ushered in the famous pax Romana–two full centuries of peace and prosperity. He instituted various social reforms, won numerous military victories and allowed Roman literature, art, architecture and religion to flourish. Augustus ruled for 56 years, supported by his great army and by a growing cult of devotion to the emperor. When he died, the Senate elevated Augustus to the status of a god, beginning a long-running tradition of deification for popular emperors.

Augustus’ dynasty included the unpopular Tiberius (A.D. 14-37), the bloodthirsty and unstable Caligula (37-41) and Claudius (41-54), who was best remembered for his army’s conquest of Britain. The line ended with Nero (54-68), whose excesses drained the Roman treasury and led to his downfall and eventual suicide.

Four emperors took the throne in the tumultuous year after Nero’s death; the fourth, Vespasian (69-79), and his successors, Titus and Domitian, were known as the Flavians; they attempted to temper the excesses of the Roman court, restore Senate authority and promote public welfare. Titus (79-81) earned his people’s devotion with his handling of recovery efforts after the infamous eruption of Vesuvius, which destroyed the towns of Herculaneum and Pompeii.

The reign of Nerva (96-98), who was selected by the Senate to succeed Domitian, began another golden age in Roman history, during which four emperors–Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius–took the throne peacefully, succeeding one another by adoption, as opposed to hereditary succession. Trajan (98-117) expanded Rome’s borders to the greatest extent in history with victories over the kingdoms of Dacia (now northwestern Romania) and Parthia. His successor Hadrian (117-138) solidified the empire’s frontiers (famously building Hadrian's Wall in present-day England) and continued his predecessor’s work of establishing internal stability and instituting administrative reforms.

Under Antoninus Pius (138-161), Rome continued in peace and prosperity, but the reign of Marcus Aurelius (161–180) was dominated by conflict, including war against Parthia and Armenia and the invasion of Germanic tribes from the north. When Marcus fell ill and died near the battlefield at Vindobona (Vienna), he broke with the tradition of non-hereditary succession and named his 19-year-old son Commodus as his successor.

Decline and Disintegration

The decadence and incompetence of Commodus (180-192) brought the golden age of the Roman emperors to a disappointing end. His death at the hands of his own ministers sparked another period of civil war, from which Lucius Septimius Severus (193-211) emerged victorious. During the third century Rome suffered from a cycle of near-constant conflict. A total of 22 emperors took the throne, many of them meeting violent ends at the hands of the same soldiers who had propelled them to power. Meanwhile, threats from outside plagued the empire and depleted its riches, including continuing aggression from Germans and Parthians and raids by the Goths over the Aegean Sea.

The reign of Diocletian (284-305) temporarily restored peace and prosperity in Rome, but at a high cost to the unity of the empire. Diocletian divided power into the so-called tetrarchy (rule of four), sharing his title of Augustus (emperor) with Maximian. A pair of generals, Galerius and Constantius, were appointed as the assistants and chosen successors of Diocletian and Maximian; Diocletian and Galerius ruled the eastern Roman Empire, while Maximian and Constantius took power in the west.

The stability of this system suffered greatly after Diocletian and Maximian retired from office. Constantine (the son of Constantius) emerged from the ensuing power struggles as sole emperor of a reunified Rome in 324. He moved the Roman capital to the Greek city of Byzantium, which he renamed Constantinople. At the Council of Nicaea in 325, Constantine made Christianity (once an obscure Jewish sect) Rome’s official religion.

Roman unity under Constantine proved illusory, and 30 years after his death the eastern and western empires were again divided. Despite its continuing battle against Persian forces, the eastern Roman Empire–later known as the Byzantine Empire–would remain largely intact for centuries to come. An entirely different story played out in the west, where the empire was wracked by internal conflict as well as threats from abroad–particularly from the Germanic tribes now established within the empire’s frontiers like the Vandals (their sack of Rome originated the phrase “vandalism”)–and was steadily losing money due to constant warfare.

Rome eventually collapsed under the weight of its own bloated empire, losing its provinces one by one: Britain around 410; Spain and northern Africa by 430. Attila and his brutal Huns invaded Gaul and Italy around 450, further shaking the foundations of the empire. In September 476, a Germanic prince named Odovacar won control of the Roman army in Italy. After deposing the last western emperor, Romulus Augustus, Odovacar’s troops proclaimed him king of Italy, bringing an ignoble end to the long, tumultuous history of ancient Rome. The fall of the Roman Empire was complete.

Roman Architecture

Roman architecture and engineering innovations have had a lasting impact on the modern world. Roman aqueducts, first developed in 312 B.C., enabled the rise of cities by transporting water to urban areas, improving public health and sanitation. Some Roman aqueducts transported water up to 60 miles from its source and the Fountain of Trevi in Rome still relies on an updated version of an original Roman aqueduct.

Roman cement and concrete are part of the reason ancient buildings like the Colosseum and Roman Forum are still standing strong today. Roman arches, or segmented arches, improved upon earlier arches to build strong bridges and buildings, evenly distributing weight throughout the structure.

Roman roads, the most advanced roads in the ancient world, enabled the Roman Empire—which was over 1.7 million square miles at the pinnacle of its power—to stay connected. They included such modern-seeming innovations as mile markers and drainage. Over 50,000 miles of road were built by 200 B.C. and several are still in use today.

HISTORY Vault: Rome: Rise and Fall of an Empire

History of the ancient Roman Empire.