Vatican City's history: a sovereign that needed a visible piece of ground

What stood on the Vatican Hill before the popes

The name is older than the Church. Under the Roman kings and the Republic, the Ager Vaticanus was the marshy ground on the right bank of the Tiber, reaching north towards the mouth of the Cremera and south at least as far as the Janiculum. From the 2nd century AD the narrower toponym Vaticanum covered an area roughly matching the present state. Tacitus recorded that soldiers who camped in "the unhealthy districts of the Vatican" in AD 69 died there in numbers, and the poet Martial complained about the wine.

Agrippina the Elder drained part of the ground and laid out gardens in the early 1st century AD. In AD 40 her son Caligula built a circus in them for charioteers, later completed under Nero. Tradition places the martyrdom of Peter in that circus during the persecution Nero ordered in AD 64, and his burial in the necropolis beside the Via Cornelia. The obelisk that stood on the circus spine was moved to its present position in St Peter's Square in 1586, by Sixtus V, using a method devised by Domenico Fontana.

The Vatican's own history treats that grave as the centre of everything built on the hill afterwards. Constantine began a five-aisled basilica over it around 324, and the necropolis was buried under the new church. Stone from the ruined circus went into the building. After raiders sacked Old St Peter's in 846, Leo IV, pope from 847 to 855, walled the district, and the enclosure took his name as the Leonine City. Excavation of the necropolis under the basilica was carried out systematically from 1939 to 1941 on the order of Pius XII.

For most of the Middle Ages the popes lived across the city at the Lateran Palace, which stayed their usual residence for about a thousand years. A first palace beside St Peter's went up under Eugene III and Innocent III in the 12th century and was extended around 1300. Then the papacy left for Avignon in 1309 and the basilica stood neglected for more than a century.

How the Papal States grew out of a donation

The territory that the popes governed as sovereigns came from outside Rome and it came as a grant. The popes had held large estates around the city, the Patrimony of St Peter, since the 4th century, but that land still lay inside the Eastern Roman Empire. In the 750s, with the Lombards threatening the whole peninsula, Stephen II appealed to the Frankish ruler Pippin III, who handed central Italy to the Roman see and set aside the Byzantine claim. Britannica dates this Donation of Pippin to 756 in its article on the Papal States and to 754 in its article on Vatican City. The same year, by the Treaty of Pavia, the Lombard king Aistulf ceded further territory.

What followed lasted until 1870 and never held a fixed shape. At its core the state took in the modern regions of Lazio, Umbria and Marche and part of Emilia-Romagna, and its reach varied with each century. Benevento was acquired in 1077. Innocent III, pope from 1198 to 1216, pressed claims in the march of Ancona, and in 1201 Otto IV acknowledged the Church's right to the duchy of Spoleto. The Avignon years, 1309 to 1377, loosened papal control to the point where Cardinal Albornoz needed a ten-year campaign, from 1353 to 1363, to reconquer it.

The return to Rome in 1377 brought the popes to the Vatican to live. Sixtus IV began the chapel named after him between 1477 and 1480, and it was inaugurated on 15 August 1483. Julius II, pope from 1503 to 1513, began pulling down Constantine's basilica to build a new one, called Raphael and Michelangelo to Rome, and in January 1506 founded the Swiss Guard as his personal bodyguard. Under Julius the Papal States stretched from Parma and Bologna in the north through Umbria to the Campagna south of Rome, much of it taken in campaigns the pope led in person. Bernini closed the square with the two curved colonnades in the middle of the 17th century.

How two popes became prisoners of France

The French Revolution showed how little the territory protected its ruler. Avignon broke from papal control in 1791 and was annexed by France. In 1798 the French took the remaining papal lands and proclaimed a Roman Republic; Pius VI refused to recognise it and was arrested. His successor Pius VII presided over Napoleon's coronation in 1804 and was taken prisoner in turn when France annexed the Papal States again in 1809. The Congress of Vienna restored them in 1815. Within eleven years two popes had been held by a secular power in spite of ruling a state of their own.

How Italian troops took Rome from Pius IX

Revolts against clerical government broke out in 1830 and 1831 and again in 1848. In February 1849 a second Roman Republic was declared and Pius IX fled the city; the French suppressed it that year, and he returned in 1850. For the movement to unify Italy the Papal States were an obstacle on two counts, Britannica notes: they cut the peninsula in half, and foreign powers kept intervening to protect papal independence.

After Austria's defeat in 1859, several papal territories voted to join the Kingdom of Sardinia. In 1860 Piedmont-Sardinia conquered the eastern two-thirds of what remained, and Bologna, Ferrara, Umbria, the Marches, Benevento and Pontecorvo were formally annexed by November. In March 1861 the first Italian parliament, sitting in Turin, declared Rome the capital of a kingdom that did not hold it. A French garrison stood between them.

The garrison was recalled after the Franco-Prussian War broke out in July 1870. Italy declared war on 10 September, the army under General Raffaele Cadorna crossed the papal frontier the next day, and it reached the Aurelian Walls on 19 September. Pius IX ordered more than token resistance, so that Rome would be seen to be taken by force and not by consent, while limiting the defence to avoid bloodshed. The breach at Porta Pia, later mythologised, was a close-range cannonade against a wall about 1,600 years old in poor repair. Papal forces lost 12 dead and 47 wounded, and the Italian troops 32 dead and 145 wounded. Rome fell on 20 September 1870, and a plebiscite in October annexed it and what was left of the Papal States to the Kingdom of Italy. The Italian army left the Leonine City itself unoccupied.

Why the popes refused the Law of Guarantees

Italy offered a settlement within months. The Law of Guarantees of 13 May 1871 gave Pius IX and his successors the use of the Vatican and Lateran palaces, the right to send and receive ambassadors and a yearly income of 3,250,000 lire. It withheld one thing, sovereignty over the palaces. The Holy See rejected the arrangement on the ground that spiritual jurisdiction required clear independence from any political power, and it refused any proposal under which a pope would become an Italian subject. The Quirinal Palace, where popes had lived since 1583, was confiscated in 1871 and became the royal palace.

Pius IX, the last ruler of the Papal States, withdrew into the Apostolic Palace and the buildings inside the Leonine walls and did not come out. Each pope after him did the same, as a self-described "prisoner in the Vatican", for close to sixty years. Italy stayed out of the Vatican's immediate boundaries and confiscated Church property across the rest of the peninsula.

The absence of territory turned out to cost the papacy very little of its diplomatic standing. Canon law treated diplomatic relations as inherent in the papacy, so the Holy See kept exchanging envoys from inside the walls. Over the 59 years in which it held no territorial sovereignty, the number of states with diplomatic relations with it, which had fallen to 16, rose to 29. The Holy See's own mission to the United Nations dates its diplomacy to the 4th century, before the Papal States existed. The 1871 law had withheld the one thing the popes lacked after 1870, a place that was visibly nobody else's.

What the Lateran Treaty actually created

Negotiations opened in 1926 between the Holy See and the Fascist government. On 11 February 1929 Cardinal Secretary of State Pietro Gasparri signed for Pius XI and Benito Mussolini for King Victor Emmanuel III. Ratifications were exchanged on 7 June 1929 and the treaty came into force that day. The package joined a political treaty to a financial convention and a concordat.

The treaty's preamble explains the state's existence in a single clause. To assure "the absolute and visible independence of the Holy See", and to guarantee its "indisputable sovereignty in international matters", it had been found necessary "to create under special conditions the Vatican City". Wikipedia's account notes that the treaty spoke of the city as a creation, not as a remnant of the Papal States. Article 2 recognised the Holy See's sovereignty in international matters as an attribute it already possessed. Article 26 declared the Roman Question "definitely and irrevocably settled", recognised the Kingdom of Italy with Rome as its capital, and abrogated the Law of Guarantees of 1871.

How the border was drawn around the walls

Annex I of the treaty, a map, fixed the boundaries, and the site of the state was chosen by what already stood there. Much of the territory lay inside the loop of fortifications built under Paul III, Pius IV and Urban VIII, which extended the walls of Leo IV. Where there was no wall the frontier followed the line of certain buildings, and for a short stretch a new wall was built. Article 5 obliged Italy to hand the ground over free of occupants and the Holy See to close off its open accesses, all except St Peter's Square. The area had belonged to the Roman rione of Borgo until 1929. The territory Italy recognised in 1929 measures 44 hectares, a figure Britannica and the Governorate both give.

The square stayed a special case. Article 3 kept it normally open to the public and under the supervision of the Italian police, whose powers stop at the foot of the steps to the basilica. Wikipedia describes a white line marking the edge of the square where it meets Piazza Pio XII; the Vatican's own history describes a strip of travertine joining the two wings of the colonnade. Several properties outside the walls, among them the papal palace at Castel Gandolfo, received extraterritorial privileges, and Britannica counts more than ten other buildings in Rome with them. The state's machinery followed quickly: a postal service on 13 February 1929, its first stamps on 1 August, and Vatican Radio in 1931.

What Italy paid and what the Church conceded

The financial convention paid 750,000,000 lire in cash on ratification, plus Italian 5% bonds, as a definitive settlement of the Holy See's claims arising from the events of 1870. Its own preamble says the pope had restricted his request "to the barest necessity", and the sum was smaller than Italy had offered in 1871. Article 24 pledged that the Holy See would take no part in temporal rivalries between states unless all parties appealed to it, and declared the city "neutral and inviolable territory". The treaty's first article reaffirmed the Catholic religion as the only religion of the Italian state, and the concordat gave canon-law marriage civil effect with no divorce (Article 34) and allowed religious instruction in state schools (Article 36). Mussolini marked the settlement with the Via della Conciliazione, an avenue running from near the Tiber to St Peter's.

How neutrality held through the Second World War

The pledge of Article 24 was tested within fourteen years. Under Pius XII the Holy See held to neutrality, and its diplomacy concentrated on keeping Rome from being bombed; it protested even when leaflets dropped by the Royal Air Force landed inside the walls. British Cabinet minutes recorded a policy of leaving the Vatican City alone on all accounts, while action against the rest of Rome would depend on how far the Italian government observed the rules of war.

In December 1942 the British envoy to the Holy See suggested declaring Rome an open city, and Mussolini rejected the idea when the Holy See put it to him. On 19 July 1943, in connection with the Allied invasion of Sicily, 500 United States Army Air Forces aircraft bombed Rome, aiming chiefly at the railway hub, and about 1,500 people were killed. Pius XII toured the damaged districts. After a second raid on 13 August, the government that had replaced Mussolini declared Rome an open city the following day, having consulted the Holy See on the wording. German troops occupied Rome after the armistice of September 1943 and Allied forces drove them out in 1944. Both sides respected the Vatican City's neutrality.

What changed after Italy rewrote the concordat

The republic kept the treaty. Its 1948 constitution states that relations between the state and the Catholic Church "are regulated by the Lateran Treaties". On 6 April 1964 the Holy See became a permanent observer at the United Nations, a status its mission describes as chosen, so that it could keep "absolute neutrality in specific political problems". In 1970 Paul VI disbanded the Pontifical Military Corps except for the Swiss Guard, and the Gendarmerie became a civilian police force. UNESCO inscribed Vatican City on the World Heritage List in 1984.

The concordat was revised in 1984, and both parties declared the principle of Catholicism as the sole religion of the Italian state "no longer in force". Britannica calls the new text the concordat of 1985 and dates the 1929 arrangement's effect to 3 June 1985. The revision ended compulsory religious education in state schools and replaced exclusive state funding of the Church with the otto per mille, under which Italian taxpayers direct 0.8% of their income tax to a recognised religious body or to a state social programme. It also ended Italian recognition of papal titles of nobility and Italy's right to raise political objections to a bishop's appointment.

How the state has rewritten its own constitution

The popes have used their sole legislative authority to restructure the state several times while leaving its purpose untouched. Since 1952 the president of the Pontifical Commission for Vatican City State has carried the functions that once belonged to a Governor, and since 2001 the same person has also held the title of President of the Governorate. The Vatican's own description of the state gives the form of government as absolute monarchy, with legislative, executive and judicial power held in full by the pope and passed to the College of Cardinals while the see is vacant.

The Law on the Government of the State, signed as a motu proprio on 25 November 2018, reorganised the Governorate and quoted the purpose of the state in the words of 1929, "to guarantee to the See of Peter absolute and visible independence". It took effect on 7 June 2019, ninety years to the day after the Lateran Treaty came into force. A motu proprio of March 2020 replaced the judicial system founded in 1987.

A Fundamental Law came into force on 13 May 2023. Its Article 8, paragraph 1, reserved the presidency of the Pontifical Commission to cardinals, and a motu proprio of 19 November 2025 repealed that paragraph. On 31 July 2026 the pope signed a new Fundamental Law, in force immediately, which folds the change into a single text: the Commission is now composed "of Cardinals and other Members, including the President", appointed for five years. The preamble describes the law's task as giving "constitutional identity to Vatican City State", and it defines the state's reach as the territory drawn by the Lateran Treaty together with the buildings where the Holy See operates under international guarantees. The population inside those 44 hectares stood at 882 on 31 December 2024.