Vatican City history, told through what you can still see

What I love about Vatican history is that you can read it vertically. Each era is built on top of the one before, and a good deal of it is still there, on show or under your feet. So rather than a list of popes, I’ll take you through it era by era and tell you what’s left of each one as you cross the square. The bare dates are in the table, and this is the thread that ties them together. If what you’re really after is why it counts as a proper state today, that’s in is Vatican City a country?.

A circus, some gardens and a grave

Before churches and palaces, this was the Ager Vaticanus, an area outside Rome with villas, roadside cemeteries and the gardens of Agrippina, Caligula’s mother. Caligula, emperor from 37 to 41, built a small circus there for training charioteers, and Nero remodelled it. By tradition, Peter was martyred beside that circus during the persecution of AD 64. No document fixes the date, and the official website says as much, speaking of what «tradition holds».

The grave itself is better documented. It’s a simple burial on the southern slope of the hill, facing the circus, over which a small shrine was raised a century later and mentioned in the late 2nd century by a priest called Gaius. Today you see it in the Vatican necropolis, and the circus has left something almost nobody connects with it, the obelisk in the middle of the square.

Constantine buries the cemetery

Around 324, shortly after the Edict of Milan in 313, Constantine began a great five-aisled church with Peter’s tomb at its exact centre. To level the site he filled in the slope and buried the cemetery, while the circus slowly fell apart, partly because its stone went into the new building. For me this is the most decisive moment of all, because it fixes the spot. Everything that followed, including the basilica you’ll walk into, was built to keep that altar above that grave.

Nothing of Constantine’s basilica still stands. It was pulled down from 1506 onwards to make way for the new one, so its footprint lies underneath rather than on view.

Walls, raids and an exile in Avignon

In 846 a Saracen raid sacked St Peter’s, and Leo IV answered with about three kilometres of walls, towers and battlements, inaugurated on 27 June 852. The area became known as the Leonine City. The Liber Pontificalis also credits the same pope with putting out the Borgo fire of 847 with a blessing, a scene Raphael’s workshop painted centuries later in one of the Raphael Rooms, for another pope named Leo.

The popes didn’t actually live here, though. Home was the Lateran. A first palace went up beside St Peter’s between the 12th and 13th centuries, and in 1309 the papacy moved to Avignon until 1377. The Vatican as a settled residence dates from the return.

When was the Vatican you see today built?

Nearly everything you’ll photograph is Renaissance or Baroque, put up in little more than a century and a half. Sixtus IV formally founded the Vatican Library in 1475 and built the chapel that bears his name between 1477 and 1480. Julius II, pope from 1503 to 1513, sped everything up. In 1506 he laid the first stone of the new basilica, welcomed the first Swiss Guards and gathered in a courtyard the ancient statues that are the seed of the Museums. Then he called in Raphael for his rooms and Michelangelo for the ceiling of the Sistine Chapel.

The basilica took a hundred and twenty years. Giacomo della Porta closed Michelangelo’s dome, Maderno lengthened the nave and raised the façade between 1608 and 1612, and Urban VIII consecrated it on 18 November 1626. Bernini laid out the square between 1656 and 1667. If you can only pick one place for this chapter, I’d choose St Peter’s Basilica, which marks its 400th anniversary with a Mass on 18 November 2026.

From the Papal States to the breach at Porta Pia

All the while, the popes were also kings of half of Italy. Historians place the first territorial core in 728, with the gift of the castles of Sutri and Blera, and by 1816, after the Congress of Vienna, the state covered Emilia-Romagna, the Marche, Umbria and Lazio. It all ended on 20 September 1870, when the bersaglieri entered Rome through the breach at Porta Pia. Rome became Italy’s capital and the Pope withdrew into the Vatican.

Italy tried to settle matters with the Law of Guarantees of 1871, granting the Pope inviolability and an annual allowance, but Pius IX rejected it two days later. So began the Roman Question, almost sixty years in which the Pope refused to recognise the state surrounding him.

1929, the year the country was born

The Lateran Pacts, signed that February by Gasparri for the Holy See and Mussolini for Italy, closed that chapter. Italy recognised the State of Vatican City under the Pope’s sovereignty, declared it neutral and inviolable for good and paid financial compensation for 1870. Ratifications were exchanged on 7 June and the Vatican flag went up the following day. The most visible trace of that deal for a visitor is the travertine strip marking the border in the square. Via della Conciliazione, which leads you there today, was cut later by demolishing the Spina di Borgo and, according to unofficial sources, finished for the 1950 Jubilee.

The 20th century and the story so far

Then came dates that still shape a visit. Pius XII ordered excavations beneath St Peter’s from 1939 to 1949, which gave us the necropolis you can tour. The Second Vatican Council opened on 11 October 1962 and closed on 8 December 1965. In 1970 Paul VI left the Swiss Guard as the only armed corps and disbanded the rest, and in 1984 UNESCO listed the whole complex as World Heritage.

The latest chapter fits into two years. Francis opened the Holy Door on 24 December 2024 and died on 21 April 2025. On 8 May 2025 Leo XIV was chosen, and he closed the Jubilee on 6 January 2026 and on 31 July brought in a new Fundamental Law. For me that’s a good reminder that this story isn’t finished, and that the world’s smallest state is still rewriting its rules in 2026. If you’d rather follow it pope by pope, from Peter onwards, there’s the list of popes.

And if you’re wondering about the Vatican catacombs, I explain why there aren’t any and where Rome’s are.

For lighter reading, there are the Vatican City facts.