Ancient Rome

The Traditional Founding of Rome

According to Roman legend, the city was founded on 21 April 753 BCE by Romulus, who — raised with his twin Remus by a she-wolf on the banks of the Tiber — killed his brother in a quarrel and named the city after himself. Archaeology instead points to villages on the Palatine Hill from around the 9th century BCE that gradually grew together into a city.

Why it matters: The 753 BCE founding legend became central to Roman identity and is still marked as Rome's birthday, even though the city's real origins lie in earlier Iron Age settlement.

How we know: The founding date and the Romulus story come from much later Roman writers and are legendary; archaeological remains attest to early settlement on the site.

The Roman Republic Is Founded

According to tradition, the Romans expelled their last king, the Etruscan Lucius Tarquinius Superbus, and replaced the monarchy with a republic. Power passed to two consuls elected each year and to the Senate, with institutions designed to prevent any one man from ruling as king.

Why it matters: The Republic's system of elected magistrates and senatorial government shaped Rome for nearly five centuries and influenced later constitutional thought.

How we know: The early Republican narrative survives mainly through later Roman historians such as Livy and blends history with tradition.

The Twelve Tables

Under pressure from the plebeians, a commission known as the decemviri drew up Rome's first written law code, inscribed on ten and then twelve bronze tablets. It set down rules on property, family authority, inheritance, and civil disputes.

Why it matters: Putting the law in writing meant citizens could be treated equally before it; the Twelve Tables became the foundation of Roman law.

The Gauls Sack Rome

A Gallic army of the Senones under the chieftain Brennus routed the Romans at the River Allia and then sacked the city itself, which had been left largely undefended. A garrison held out on the Capitoline Hill until the Romans paid a ransom in gold for the Gauls to withdraw.

Why it matters: The traumatic sack — Rome's only fall to a foreign enemy for the next eight centuries — spurred the Romans to strengthen their walls and reform their army.

The First Punic War Begins

Rome and Carthage went to war over Sicily after both were drawn into a dispute at Messana. The long conflict (264–241 BCE) was fought on land and, decisively, at sea, forcing Rome to build its first major navy.

Why it matters: Victory gave Rome its first overseas province and opened a century-long struggle with Carthage for control of the western Mediterranean.

Hannibal Invades Italy: The Second Punic War

The Carthaginian general Hannibal marched an army — famously with war elephants — over the Alps into Italy, crushing Roman forces at the Trebia, Lake Trasimene, and catastrophically at Cannae in 216 BCE. Rome recovered, took the war to Africa, and Scipio Africanus defeated Hannibal at Zama in 202 BCE.

Why it matters: Surviving Hannibal's invasion and winning the war confirmed Rome as the dominant power of the western Mediterranean.

The Destruction of Carthage

Urged on by Cato the Elder's refrain that 'Carthage must be destroyed,' Rome besieged and in 146 BCE stormed the city in the Third Punic War, razing it and enslaving the survivors. Its territory became the Roman province of Africa.

Why it matters: The annihilation of its great rival left Rome the unrivalled power of the Mediterranean.

Tiberius Gracchus and the Reform Crisis

As tribune in 133 BCE, Tiberius Gracchus pushed through a law redistributing public land to the poor, bypassing a hostile Senate by appealing directly to the popular assembly. He and some 300 supporters were killed in the political violence that followed.

Why it matters: The killing of a tribune over reform opened a century of political violence that would ultimately destroy the Republic.

Caesar Crosses the Rubicon

Ordered by the Senate to give up his command, Julius Caesar instead led his army across the Rubicon, the small river marking the northern boundary of Italy — an act of open rebellion that plunged Rome into civil war against Pompey and the Senate.

Why it matters: Caesar's victory in the civil war effectively ended the Republic's traditional government and set Rome on the road to one-man rule.

The Assassination of Julius Caesar

Having been named dictator for life, Julius Caesar was stabbed to death by a group of senators led by Brutus and Cassius at a meeting of the Senate on the Ides of March — 15 March — 44 BCE.

Why it matters: Rather than restoring the Republic, the assassination set off new civil wars that ended with the rise of Caesar's heir, Octavian.

The Battle of Actium

In a naval battle off the western coast of Greece, the fleet of Octavian, commanded by his admiral Agrippa, defeated the combined forces of Mark Antony and Cleopatra VII of Egypt. The pair fled and took their own lives the following year.

Why it matters: Actium left Octavian sole master of the Roman world, ending the civil wars and clearing the way for the Empire.

Augustus, the First Roman Emperor

In 27 BCE the Senate granted Octavian the honorific name Augustus and a suite of powers. Presenting himself not as a king but as princeps — 'first citizen' — he became in effect Rome's first emperor while preserving the outward forms of the Republic.

Why it matters: Augustus founded the Roman Empire and the Principate, beginning roughly two centuries of relative stability known as the Pax Romana.

The Great Fire of Rome

A fire that broke out near the Circus Maximus in July 64 CE burned for days and devastated much of Rome. Ancient sources disagree on its cause; the emperor Nero, later rumored to have started it, instead blamed and violently persecuted the city's Christians.

Why it matters: The fire and its aftermath — the rebuilding, Nero's lavish Golden House, and the scapegoating of Christians — became a notorious episode of Nero's reign.

The Destruction of the Second Temple

During the First Jewish–Roman War, the future emperor Titus besieged Jerusalem and, in 70 CE, his legions captured the city and destroyed the Second Temple by fire.

Why it matters: The Temple's destruction was a turning point for Judaism — hastening the shift toward rabbinic Judaism — and a stark display of Roman power over a rebellious province.

Vesuvius Buries Pompeii

The eruption of Mount Vesuvius in 79 CE buried the Roman towns of Pompeii and Herculaneum under ash and volcanic debris, killing many inhabitants and sealing the sites in remarkable detail.

Why it matters: Rediscovered and excavated from the 18th century onward, the buried cities are among the most vivid windows we have into everyday Roman life.

How we know: Excavations since the 18th century and an eyewitness account by Pliny the Younger document the eruption; the traditional 24 August date is debated, with some evidence pointing to autumn 79 CE.

The Colosseum Is Inaugurated

Begun under the emperor Vespasian, the Flavian Amphitheatre — the Colosseum — was inaugurated by his son Titus in 80 CE with a hundred days of games. The vast stone arena could hold tens of thousands of spectators for gladiatorial combat, animal hunts, and public spectacles.

Why it matters: The Colosseum became the enduring symbol of imperial Rome and remains one of its most famous monuments.

The Empire at Its Greatest Extent under Trajan

Under the emperor Trajan, whose conquests included Dacia and, briefly, Mesopotamia, the Roman Empire reached its greatest territorial extent by 117 CE, stretching from Britain to the Persian Gulf.

Why it matters: Trajan's reign marked the high-water mark of Roman expansion; his successor Hadrian would consolidate the frontiers rather than extend them.

Hadrian's Wall Is Begun

Around 122 CE, following the emperor Hadrian's visit to Britain, the Romans began building a stone wall running some 73 miles (120 km) coast to coast across northern Britain to mark and guard the frontier.

Why it matters: Hadrian's Wall embodied a new imperial strategy of holding fixed frontiers rather than expanding endlessly, and is the best-known surviving Roman frontier work.

The Antonine Plague

A devastating epidemic — likely smallpox — swept the Roman Empire from about 165 CE, carried by armies returning from the east. Documented by the physician Galen, it killed millions over the following years during the reign of Marcus Aurelius.

Why it matters: The plague strained the Empire's population, army, and economy at the very height of its power, foreshadowing the crises to come.

How we know: The physician Galen described the disease first-hand; modern estimates of the death toll vary widely.

The Crisis of the Third Century

After the murder of the emperor Severus Alexander in 235 CE, the Empire fell into a half-century of near-collapse: dozens of short-lived 'barracks emperors,' repeated invasions, plague, economic breakdown, and the temporary breakaway of the Gallic and Palmyrene empires.

Why it matters: The Empire barely survived, and only sweeping reforms at the century's end restored stability — on very different foundations.

Diocletian and the Tetrarchy

Coming to power in 284 CE, Diocletian ended the crisis with sweeping reforms. He divided rule of the Empire among four emperors — two senior Augusti and two junior Caesars — in a system known as the Tetrarchy, and reorganized the army, provinces, and taxation.

Why it matters: Diocletian's reforms stabilized the Empire and formalized the split between its western and eastern halves.

Constantine, the Milvian Bridge, and the Edict of Milan

In 312 CE Constantine defeated his rival Maxentius at the Battle of the Milvian Bridge — by tradition after a vision of the cross — and the following year he and Licinius issued the Edict of Milan, granting toleration to Christianity and ending its persecution.

Why it matters: Constantine's embrace of Christianity set the religion on the path from persecuted sect to the dominant faith of the Roman world.

The Founding of Constantinople

In 330 CE Constantine dedicated a new imperial capital on the site of the Greek city of Byzantium, on the Bosporus. He called it 'New Rome,' but it soon took his own name — Constantinople.

Why it matters: The new eastern capital would outlast Rome itself by nearly a thousand years as the heart of the Byzantine Empire.

Christianity Becomes the State Religion

In 380 CE the emperor Theodosius I issued the Edict of Thessalonica, making Nicene Christianity the official religion of the Roman Empire. Further laws soon restricted and then banned public pagan worship.

Why it matters: Within a lifetime of the Edict of Milan, Christianity went from merely tolerated to mandatory, ending Rome's long tradition of religious pluralism.

The Visigoths Sack Rome

In August 410 CE the Visigoths under King Alaric entered Rome and sacked it over three days — the first time the city had fallen to a foreign enemy in some 800 years, though by then it was no longer the imperial capital.

Why it matters: The sack shocked the Roman world and stands as a milestone in the decline of the Western Empire.

The Fall of the Western Roman Empire

In 476 CE the Germanic commander Odoacer deposed the young emperor Romulus Augustulus and, rather than name a successor, sent the imperial regalia to Constantinople and ruled Italy as king. No emperor reigned in the West thereafter.

Why it matters: By convention 476 CE marks the end of the Western Roman Empire and of classical antiquity — though the eastern (Byzantine) Empire would endure for another thousand years.

How we know: Historians treat the 'fall' as a long process; 476 is a conventional marker, and some date the end instead to 480 CE with the death of Julius Nepos.