Rome — Capital of Italy

Rome's traditional founding date, 21 April 753 BCE, comes from later Roman legend (the Romulus and Remus myth) rather than archaeological record, but excavations on the Palatine Hill have confirmed continuous settlement stretching back to roughly that period, and the city went on to become capital of a kingdom, then a republic, then an empire that at its height controlled territory from Britain to the Persian Gulf — a scale of ancient political centrality no other modern national capital can claim as directly its own history.

After the Western Roman Empire's collapse in the 5th century CE, Rome's political importance receded sharply for centuries, its population falling from perhaps a million at its imperial peak to a small fraction of that by the early medieval period, even as it retained enormous religious significance as the seat of the Papacy, which governed Rome and the surrounding Papal States as an independent temporal power for over a thousand years, well into the modern era.

Rome only became capital of a unified Italian state relatively late in the unification process: when the Kingdom of Italy was proclaimed in 1861, its capital was initially Turin, then Florence from 1865, because Rome itself remained under Papal control, defended in part by French troops loyal to Napoleon III. It was not until Italian troops breached the city walls at Porta Pia on 20 September 1870 — timed to take advantage of France's withdrawal of its garrison during the Franco-Prussian War — that Rome was annexed to the Kingdom of Italy and became its capital the following year, completing unification and ending over a millennium of Papal temporal rule over the city.

The Papacy's loss of Rome created decades of unresolved tension between the Italian state and the Catholic Church, resolved only by the 1929 Lateran Treaty between Mussolini's government and Pope Pius XI, which created Vatican City as a fully independent sovereign state — a tiny enclave entirely surrounded by Rome — formally settling the 'Roman Question' that had simmered since 1870 by giving the Pope sovereign territory of his own rather than authority over the city itself.

Modern Rome functions as Italy's political capital, seat of the Italian Parliament and presidency, while also remaining one of the world's most visited cities for its ancient ruins (the Colosseum, the Forum, the Pantheon) layered directly alongside Renaissance and Baroque-era churches and palaces — a physical density of historical eras in one city that has few real parallels among other national capitals worldwide.

Rome's status as an ancient imperial capital gave it engineering infrastructure — aqueducts, road networks radiating outward across the empire, sewer systems like the Cloaca Maxima — so far ahead of medieval European norms that several of these Roman-era systems remained in partial use, or were rediscovered and restored, well into the modern era, a continuity of practical infrastructure unusual among world capitals.

Building height in central Rome remains legally restricted to this day, largely to protect sightlines to the city's ancient and Renaissance-era skyline, meaning Rome's modern skyscraper and business districts — most notably the EUR district, originally built under Mussolini for a 1942 world's fair that was cancelled by the war — have been deliberately located away from the historic core rather than layered on top of it.

Rome's population declined dramatically after the fall of the Western Roman Empire, from well over half a million at its imperial height to perhaps only around 20,000-30,000 residents by the early medieval period, huddled largely within a bend of the Tiber River amid the ruins of the much larger ancient city — a stark demographic collapse the city did not fully recover from, in relative terms, until the population growth of the 19th and 20th centuries.

The Trevi Fountain, completed in 1762 after decades of intermittent construction, sits at the terminus of the Aqua Virgo, an aqueduct originally built in 19 BCE under Augustus — meaning the fountain's water source traces back, with periods of interruption and repair across two millennia, to one of ancient Rome's original imperial-era aqueducts.