Tens of thousands of mourners have paid last respects to Pope Francis at St Peter's Basilica, on the first of three days of lying in state.
Pilgrims and tourists queued for hours to file past the open coffin of the Argentine pontiff, who died on Monday aged 88.
"We wanted to say thank you to one of the most humble popes," said Portuguese medical student Francisca Antunes, 21, after leaving the Vatican basilica with a friend.
"It felt really good to be in there," she said.
By 7.45pm local time (6.45 Irish time), almost nine hours after the doors of the basilica opened to the public, more than 19,400 people had paid their respects, the Vatican said.
Simonetta Marini, a 67-year-old from Rome, praised Pope Francis's human touch and defence of the world's underdogs, which helped steer the Catholic Church towards a more inclusive, compassionate path.
"I came to say a last goodbye to a great man. He stood for the people," Ms Marini said.
The body of the 88-year-old pope, who died two days ago in his rooms at the Vatican's Santa Marta guesthouse after suffering a stroke, was brought to St Peter's in a solemn procession earlier today.
Cardinals, bishops, friars and Swiss Guards walked slowly into the vast square in front of the basilica as a choir chanted psalms and prayers in Latin while a bell gently tolled.
As the coffin crossed St Peter's Square, a crowd of several thousand broke into repeated applause - a traditional Italian sign of respect at such events.
"Dear brothers and sisters, with deep sorrow we now accompany the mortal remains of our Pope Francis to the Vatican Basilica," said Irish-born Cardinal Kevin Farrell, who holds the post of camerlengo, or chamberlain, at the start of the ceremony.
Vatican officials helped 14 white-gloved, black-suited pallbearers carry the coffin up a stone incline, before the procession passed through St Peter's giant bronze doors and into the hushed interior of the ornate, cavernous church.
As the formal ceremony to bring the pope's body to the basilica was ending, Sr Genevieve Jeanningros, a nun from the Roman seaside town of Ostia, stood by his casket and cried.
Sr Jeanningros, known for her work with the LGBTQ+ community, had hosted Pope Francis for visits in Ostia several times.
The pontiff had only recently left hospital after five weeks being treated for double pneumonia. He last appeared in public on Sunday, when he delighted onlookers gathered to celebrate Easter by being driven around the packed square in his white, open-topped popemobile.
Dressed in his papal vestments - a red chasuble, white mitre and black shoes - and with a rosary wrapped between his fingers, the Pope's body has been laid out in a red-lined wooden coffin.
For the next three days, it will rest on a low bier before the Altar of the Confession underneath a dome painted by Michelangelo, before being closed at 8pm on Friday evening ahead of Saturday's funeral.
Italian Prime Minister Giorgia Meloni paid tribute at a special joint session of parliament in Rome, before going to pay her own respects at St Peter's.
She described Pope Francis as a "determined" man who nevertheless made others feel at ease.
"With him you could talk about everything. You could open up, and tell your story without filters or fear of being judged," she said.
The Vatican had originally planned to close today's visits at midnight, but said it may extend the timeframe due to a "high flow" of pilgrims.
A retired Irish couple in their 60s said that despite being on holiday in Rome, it was a "priority" to come see Pope Francis, whom they said had made efforts in their country to address the problem of clerical sexual abuse.
"He was a great man, a great advocate for the poor, the underprivileged and those who suffered at the hands of his flock," said Clíodhna Devlin.
"He's like a member of the family. Somebody very close to our hearts, somebody who made the Church very accessible to everybody and inclusive to everybody," said British woman Rachel McKay.
Watch: The moment Pope Francis's coffin is placed before the Altar of the Confession in St Peter's Basilica
The funeral on Saturday will draw heads of state and government from around the world, including US President Donald Trump, who clashed repeatedly with the Pope on social issues.
President Michael D Higgins, Taoiseach Micheál Martin and Tanáiste Simon Harris are all expected to attend.
Leaders from Italy, France, Germany, Britain, Ukraine, EU institutions and Francis's home country of Argentina have also confirmed their attendance.
At least 200,000 people are expected to attend the outdoor service, the head of Italy's civil protection agency, Fabio Ciciliano, told the Corriere della Sera newspaper.
Watch: Thousands queue to pay respects to Pope Francis in the Vatican
Italy is preparing for a major security operation for the funeral, with the weekend already due to be busy because of the public holiday on Friday 25 April.
Barriers have already been installed inside and outside the basilica, security checks have been increased and staff have been distributing bottles of water due to the warm weather.
Five days of national mourning were declared - longer than the three days observed for Pope John Paul II in 2005, but less than the week declared for Francis by his native Argentina.
Interior Minister Matteo Piantedosi said authorities were expecting between 150 to 170 foreign delegations.
Read More:
Security in Rome to intensify ahead of Pope's funeral
Who might succeed Pope Francis? Some possible candidates
Climate justice central to Francis's message
A conclave to choose the new pope is not expected to start before 6 May.
Cardinals around the world have already been sent letters from the Holy See instructing them to return to Rome to select a new pope.
Only those under the age of 80 are eligible to vote for a pope in the conclave, which should begin no less than 15 days and no more than 20 after the death of the pope.
In the meantime, in the period known as the "sede vacante" (vacant seat) for the global Catholic Church, Cardinal Farrell is in charge of day-to-day affairs.
About 60 cardinals of all ages already in Rome met yesterday to choose the funeral date, in a so-called "general congregation".
A second meeting of cardinals is scheduled for this afternoon led by the Cardinal Farrell.
Afterward his funeral on Saturday, Pope Francis's coffin will be taken to his favourite church, Rome's papal basilica of Santa Maria Maggiore, where it will be interred in the ground and marked by a simple inscription: Franciscus.
He will become the first pope in more than 100 years to be buried outside the Vatican.
