The history of the Vatican City

Vatican City is the smallest sovereign state in the world, a walled enclave of 44 hectares inside Rome with fewer than a thousand residents. Its history, though, is that of the papacy, which grew from the leadership of a persecuted religious community into the government of a large Italian state. For over a thousand years the popes ruled the Papal States across central Italy, until the unification of Italy swept them away in 1860 and 1870. The modern state was created by the Lateran Treaty of 1929 to guarantee the pope's independence, and it remains an absolute elective monarchy, the temporal seat of the Holy See and the Catholic Church.

In antiquity the Ager Vaticanus was a low, marshy district on the west bank of the Tiber, outside the city proper and long considered unhealthy. In the early first century CE Agrippina the Elder laid out gardens there, and her son Caligula built a racing circus, later finished by Nero. The obelisk that now stands in St Peter's Square came from Egypt to decorate it. After the great fire of 64, Nero blamed the Christians, and many were killed in the circus. Christian tradition holds that the apostle Peter was crucified there and buried in the cemetery beside it, on the road known as the Via Cornelia.

The site changed after Constantine I, the first Christian emperor of the Roman Empire, legalised Christianity in 313. Around 324 he began a five-aisled basilica over the shrine believed to mark Peter's grave, levelling the hillside and part of the cemetery to build it. Old St Peter's became one of the great pilgrimage churches of Christianity. The popes themselves, however, lived for most of the next thousand years at the Lateran Palace on the other side of Rome, which Constantine had also given to the church. Excavations ordered by Pius XII between 1939 and 1941 uncovered the ancient necropolis beneath the basilica.

The bishops of Rome became landowners in late antiquity, receiving estates across Italy and beyond. After the Western Empire fell, Italy passed to the Ostrogoths, then to the Byzantine emperors, and from 568 was invaded by the Lombards. As Byzantine power weakened, the popes took on more and more of the government of Rome and its surrounding duchy. When the Lombards captured Ravenna in 751, Pope Stephen II turned to the Franks. Pepin the Short defeated the Lombards in 754 and 756 and gave the pope the conquered lands, an act known as the Donation of Pepin, which is usually taken as the legal beginning of the Papal States. In 800 Pope Leo III crowned Charlemagne emperor in St Peter's.

After Arab raiders sacked Old St Peter's in 846, Pope Leo IV enclosed the Vatican district with walls, completed in 852 and known as the Leonine City. Through the Middle Ages the popes struggled with the Roman nobility and with the emperors of the Holy Roman Empire over who truly ruled their lands, and much of the territory was held in practice by local lords. From 1309 to 1377 the popes lived at Avignon in southern France. On their return to Rome they made the palace beside St Peter's their main residence.

The Renaissance popes turned the Papal States into a real territorial power. Alexander VI and Julius II, the "warrior pope", fought to bring rebellious cities under control, and by 1649 the state covered most of central Italy, from Lazio through Umbria and the Marche to Bologna and Ferrara. They also rebuilt the Vatican. Sixtus IV built the Sistine Chapel from 1477, and Julius II began a new St Peter's in 1506, hired Michelangelo to paint the Sistine ceiling and Raphael to fresco the papal apartments, and founded the Swiss Guard. The basilica was finished under Michelangelo's dome and consecrated in 1626, and Bernini's colonnaded square was completed in the 1660s. In 1527 the troops of Emperor Charles V sacked Rome, and the Swiss Guard lost most of its men defending Pope Clement VII.

Revolutionary France seized Avignon in 1791 and invaded the Papal States in 1796 to 1798, declaring a Roman Republic. Napoleon annexed the remaining papal lands to his empire in 1809 and held Pius VII prisoner, but the Congress of Vienna restored the state in 1815. The restored papal government was conservative and unpopular, and revolts in 1831 and 1848 were put down with Austrian and French help. In 1849 a second Roman Republic briefly drove out Pius IX.

During the unification of Italy, the Kingdom of Sardinia conquered most of the Papal States in 1860, leaving the pope only Rome and Lazio, protected by a French garrison. When France withdrew its troops at the start of the Franco-Prussian War, Italian forces entered Rome on 20 September 1870 after a brief bombardment at Porta Pia, and the city became the capital of Italy. Pius IX refused to accept the loss or the Law of Guarantees of 1871, which offered him an annual payment and personal immunity. He and his successors remained inside the Vatican as self-described prisoners, and the unresolved dispute became known as the Roman Question.

The Roman Question was settled by the Lateran Pacts, signed at the Lateran Palace on 11 February 1929 by Cardinal Pietro Gasparri for Pius XI and by Benito Mussolini for King Victor Emmanuel III. The treaty recognised the Holy See's full sovereignty over a new State of Vatican City, gave extraterritorial status to papal properties such as the Lateran basilica and the summer residence at Castel Gandolfo, and in return the papacy recognised the Kingdom of Italy with Rome as its capital. A financial convention compensated the Holy See for its lost territories with 750 million lire in cash and bonds worth a further billion lire, and a concordat made Catholicism Italy's state religion and gave the church a role in education and marriage. The pacts took effect on 7 June 1929. Mussolini's regime then cut the Via della Conciliazione through the old Borgo district to make a grand approach to St Peter's.

The new state acquired its own flag, coins, stamps, railway station and, from 1931, Vatican Radio. During the Second World War it remained neutral and was respected as such by both sides, even during the German occupation of Rome from 1943 to 1944. Pius XII's response to the Holocaust remains the subject of debate: critics fault his public silence about the murder of the Jews, while defenders point to the quiet sheltering of Jews in church buildings in Rome and argue that open protest would have provoked reprisals.

The Second Vatican Council, held in St Peter's from 1962 to 1965, reshaped the Catholic Church's liturgy and its relations with other faiths. In 1984 a revised concordat with Italy ended Catholicism's status as the state religion, and the same year UNESCO listed the whole of Vatican City as a World Heritage Site. John Paul II, elected in 1978 as the first non-Italian pope since 1523, travelled the world and supported the Solidarity movement in his native Poland. His long reign also saw scandals over Vatican finances that continued into later decades.

Benedict XVI became in 2013 the first pope to resign since the Middle Ages, and the Argentine Francis became the first pope from the Americas. His reign brought reforms of the Vatican's finances and administration, alongside continuing reckoning with clerical sexual abuse. Francis died on 21 April 2025, and on 8 May 2025 the cardinals elected Robert Francis Prevost of Chicago, an Augustinian who had served many years in Peru, as Leo XIV, the first American pope. In November 2025 he changed the law to allow women to lead the commission that governs the city state. Today the pope holds full legislative, executive and judicial power over Vatican City, while the Holy See conducts the diplomacy of the church with most of the world's states.