At Pope Francis's funeral, Cardinal Giovanni Battista Re urged world leaders and mourners to "build bridges, not walls", echoing the late pontiff's calls for migrant care, peace and climate action.
Presiding over the Requiem Mass in St Peter's Square, the 91-year-old prelate delivered a message both political and pastoral.
"A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian", he told the crowd, echoing Francis's criticism of US President Donald Trump's immigration policies first voiced in 2016.
Mr Trump, who clashed publicly with the Pope over migrant compassion, sat just yards from the altar.
Ukrainian President Volodymyr Zelensky, who had not confirmed if he would attend, appeared to receive a round of applause when he stepped out of St Peter's Basilica. The crowd of assembled world leaders clapped as he walked down the steps into St Peter's Square.
88-year-old Pope Francis, who died on Easter Monday, has been hailed for his leadership of the Church, proving popular among young people and known for his outreach to those most in need in society.
As the funeral began, thousands of mourners and visiting dignitaries fell silent as a simple wooden casket, topped with a large cross, was carried into view by a dozen pallbearers.
Reflecting on the Pope's final public appearance on Easter Sunday, Cardinal Re told the assembled crowd: "Despite his serious health problems, he wanted to give us his blessings from the balcony of St Peter’s Basilica, then came down to greet us from his open Popemobile as a large crowd gathered for the Easter Mass."
Giving a homily in Italian, he highlighted the late pontiff's lifelong call for peace.
"War always leaves the world worse than it was before: it is always a painful and tragic defeat for everyone," he said.
Cardinal Re also praised Francis's "charisma of welcome and listening" and his efforts to shed "light on the problems of our time with the wisdom of the gospel".
As the service drew to a close, the crowd applauded as the pontiff’s coffin was brought back into St Peter’s Basilica - the first pope in more than a century not to be entombed there.
Instead, he has chosen the Santa Maria Maggiore Basilica as his final resting place, a fifth-century church located in the centre of Rome that already holds the tombs of seven popes.
Watch: Northern Irish couple thrilled to see so many young people participate in Pope's funeral
One of the first dignitaries to arrive for the Requiem Mass was former US President Joe Biden, accompanied by his wife Jill, stepping onto the cobbled esplanade amid tight security and cheering crowds.
Ireland's delegation was led by President Michael D Higgins, with Taoiseach Micheál Martin and Tánaiste Simon Harris also in attendance.
Watch: Taoiseach Micheál Martin says it is an 'honour' to represent Ireland at Pope Francis's funeral
Mr Harris said it "was an honour and a privilege" to attend today's funeral of "a remarkable spiritual leader who left an indelible mark on our world".
"The sadness we have all felt at his passing has been eased somewhat by the widespread celebration of his life and his achievements that we have witnessed since his death."
Watch: World leaders arrive for Pope Francis's funeral
UK Prime Minister Keir Starmer and French President Emmanuel Macron were also among the mourners alongside Scotland's First Minister John Swinney and Michelle O’Neill, the First Minister of Northern Ireland.
The Vatican said 250,000 people attended the funeral.
Crowds started to gather in the nearby streets before 5am, with nuns, priests and lay people making their way towards St Peter's Square.
A tight security presence saw roads in the vicinity closed as Italian police managed the huge numbers keen to get as close as they could to the square.
Over a three-day lying-in-state, some 250,000 mourners paid their respects to Pope Francis, which ran overnight Wednesday due to high demand.
The final mourners had a chance to see the Pope in the grand surroundings of St Peter's Basilica, before his coffin was closed in private yesterday evening.
Britain's Prince William travelled to the Vatican to represent King Charles, the first time he has done so at an international funeral.
Watch: The gates open in St Peter's Square for mourners to attend the Pope's funeral
While today is the first of nine official days of mourning, speculation regarding the next pope is likely to begin soon after the funeral.
Conclave, the secret meeting of cardinals to elect Francis's successor, is thought likely to begin on 5 May.
One Vatican expert has said she thinks it is "totally unpredictable" at this point as to who the next pope might be.
UK theologian Professor Anna Rowlands said: "That's partly because the process is genuinely both secret, so it happens in private, but also because the make-up of this College of Cardinals is very different from anyone that's been here to elect a pope before.
"It's going to be, I think, a surprise conclave, that is totally unpredictable at this point, but I think will produce, potentially, a really interesting candidate who possibly none of us will know," she added.
Irish-born Cardinal Kevin Farrell - the Camerlengo or senior Vatican official - has been responsible for carrying out the administrative and financial duties of the Holy See until a new pope takes over.
He had the role of announcing the Pope's death on Easter Monday, coordinating meetings with the cardinals ahead of the conclave and ensuring the Sistine Chapel is ready to accommodate them when that process begins in the coming weeks.
The sign of a new pope having been elected will be the emergence of white smoke from a chimney of the Sistine Chapel while, soon after, an announcement in Latin of "Habemus Papam" - meaning "we have a pope" is made alongside the chosen pontiff's appearance on the balcony of St Peter's Basilica.
