VATICAN CITY — As pilgrims and world leaders alike prepare to say goodbye to Pope Francis at his funeral Saturday, Rome is racing to get ready.

The city is blocking off roads and calling in police officers from across the country. It is installing screens for overflow crowds. It is working to slot in an influx of private and government jets escorting kings and queens, prime ministers and presidents, including Donald Trump. The funeral will have the security concerns of a United Nations assembly and the crowd scale of a massive music festival — and it is taking place with less than a week’s notice, following Francis’s death on Monday at age 88.

“It is an activity, as you have seen in recent days, that is particularly complex,” said Fabio Ciciliano, the head of Italy’s civil protection service.

Francis’s funeral is likely to be the largest single-day event at the Vatican in 20 years, since the funeral of Pope John Paul II. Italian media have said authorities are expecting at least 200,000 people — a crowd that would spill out of the colonnaded piazza of the tiny city-state and flow into the streets of Rome.

After the funeral, which starts at 10 a.m. local time and is expected to last 90 minutes, Francis’s coffin will be transferred through the city to the Papal Basilica of Saint Mary Major, where the pope asked to be buried.

He will be the first pope in more than a century to be buried outside the Vatican’s ancient walls. And the resulting procession — about four miles — will add an extra element of complexity to the day while allowing crowds in central Rome to also say goodbye.

Francis’s funeral might not quite match the size of John Paul II’s, which attracted at least 300,000 people and marked a global outpouring for a towering Cold War-era figure. The Vatican said that funeral involved 159 foreign delegations, not to mention 11,900 police officers and security officials and 6,000 journalists. Authorities set up 3,600 portable toilets and distributed 3 million free bottles of water.

Francis’s funeral will have a banner list of attendees — with much intrigue about how world leaders will interact at a time of high geopolitical tensions. Trump said he will be there with first lady Melania Trump. Ukrainian President Volodymyr Zelensky, who had a contentious White House meeting with Trump in February, will also attend. Others on the expected guest list: French President Emmanuel Macron; U.N. Secretary General António Guterres; Prince William, the Prince of Wales; and Javier Milei, the president of Francis’s native Argentina.

Former president Joe Biden and former first lady Jill Biden will also attend, according to a Biden spokesperson. The Vatican says that Milei and Italy’s president, Sergio Mattarella, will have front-row seats. Other seats will be filled with the reigning sovereigns, followed by the heads of state and government — in alphabetical order, according to the country name in French.

Fifty heads of state, 10 reigning sovereigns and 130 delegations are confirmed to attend the funeral, according to the Office of Protocol of the Vatican Secretariat of State.

Russian President Vladimir Putin, who met several times with Francis during the pope’s 12-year pontificate, will not be attending. Putin is subject to an International Criminal Court arrest warrant over alleged war crimes in Ukraine. (Zimbabwe’s then-president Robert Mugabe attended John Paul II’s funeral despite a European Union travel ban. Italy allowed him to land because he was going to the Vatican, which is not part of the E.U.)

Two years ago, the Catholic Church held a funeral for Benedict XVI. But the circumstances of that event were unusual: Benedict had abdicated in 2013 and had spent nearly a decade as a mostly secluded pope emeritus. Only 50,000 people attended his funeral on a foggy January morning.

This time, the spring weather figures to be ideal — with a Saturday high of 72 degrees. The city was already buzzing with religious pilgrims because of the once-every-25-years jubilee. Rome had been expecting huge crowds this year and had conducted major public works upgrades.

Fortuitously, one of those projects involved reducing car traffic just outside the Vatican — allowing a free flow of pedestrians from the fortress of Castel Sant’Angelo to St. Peter’s Square.

Anthony Faiola contributed to this report.