Pope John Paul II's body has arrived in St Peter's Basilica, where it is to lie in state until his funeral on Friday.
Swiss Guards escorted the procession from a palatial hall in the Vatican, accompanied by many of the cardinals who will choose the Pope's successor.
The first of thousands of Roman Catholics have begun filing past the Pope's body to pay their respects.
The pontiff died on Saturday at the age of 84 after a 26-year reign, the third longest in history.
Queues stretching back into St Peter's Square began to move slowly into the basilica when the doors were opened shortly before 2000 (1900 BST) on Monday.
The basilica will remain open until Friday's funeral, closing only between 0200 and 0500 each day, for maintenance.
Rome expects up to two million extra visitors coming to pay their respects.
It has so far been confirmed that 22 heads of state will attend the funeral.
The vast procession wound its way down ornate staircases before emerging into the sunlight of the crowded square to a tolling bell and a Latin chant, finally passing through the doors of the basilica.
WHAT HAPPENS NEXT
Lying in state from Monday evening
Funeral on Friday at 1000 (0800 GMT)
Election of new Pope begins 15-20 days after death
John Paul's body, carried by 12 pallbearers, was displayed in his papal robes and mitre clutching a set of Rosary beads.
After a short religious service in the basilica, Cardinals approached the Pope's bier to bow.
Church leaders, Vatican staff and prominent Italians earlier viewed the Pope's body in the Clementine Hall, with bishops and priests praying aloud as they knelt beside the Pope's remains.
St Peter's Square is dotted with impromptu memorials of flowers and candles, while handwritten messages are stuck to street lamps with wax.
"Goodbye, father, hero, friend," read one message.
Michaela Wiemann, a German missionary among those watching the procession, said that seeing the Pope's face in death had filled her with "the joy that he radiates".
"Seeing all the people here, that's the real Church," she told AFP news agency.
The funeral, scheduled for 1000 (0800 GMT), is likely to see one of the biggest gatherings of world leaders in recent times.
Cardinal Joseph Ratzinger, tipped by some as his successor, will preside over the open-air ceremonies on the steps of the basilica.
John Paul II will be buried in the crypt beneath St Peter's Basilica immediately following the funeral and a Requiem Mass, the Vatican's spokesman announced.
The Pope had not stated any wishes about his last resting place, Joaquin Navarro-Valls said, and the Vatican would therefore "follow tradition" by burying him at the basilica.
Some had speculated the Polish-born Pope might have wanted to be interred in his beloved native country.
Mr Navarro-Valls said 65 cardinals had met in Rome for about two and a half hours to read the Pope's will and fix the funeral date.
The meeting was the first time the "princes of the Church" had met since his death and more are due to arrive, coming from across the world.
With Roman hotels and guest houses already full, makeshift shelters are being created for visitors at sports grounds.
Giant video screens may be installed to relay the ceremonies.
Cardinals will deal with the day-to-day running of the Church until they elect a new pope at a conclave later in the month.
BBC religious affairs correspondent Jane Little says preliminary meetings provide an opportunity to raise general concerns about the shape and future of the Church.
There are nearly 200 cardinals involved in the consultations, but only 117 of them are under the age of 80 and therefore entitled to vote for a new pope.
KEY AREAS WITHIN THE VATICAN
1: Papal Apartments: Where John Paul II died, 2 April 2005
2: Clementine Hall: Cardinals and other officials view Pope's body
3: St Peter's Basilica: Pope to lie in state and be buried here
4: Sistine Chapel: Cardinals to gather here to pick successor
5: St Peter's Square: Funeral mass to be held here on Friday