Pope John Paul II has been lying in state in St Peter's Basilica
It promises to be one of the largest funerals in history.
More than two million people have already filed past the body of John Paul II.
Thousands more pilgrims are on their way, especially from Poland, in the hope of getting here in time for the funeral mass.
But for many of those who have crossed countries and continents to get to Rome, this will be a "virtual" funeral.
The sea of people that has engulfed the Vatican this week simply cannot be fitted into the available space.
Even when jammed to capacity, St Peter's Square can accommodate no more than a quarter of a million, and that will be quite a squeeze.
Others may get a glimpse of the proceedings from the Via Della Conciliazione, the long road that stretches from the square back towards the River Tiber.
The only other vantage points are the rooftops and balconies of hotels and offices around the Vatican.
All the prime locations have been hired, at great expense, by television companies who plan to broadcast the service live to a worldwide audience of billions.
In Rome, every large public square will be provided with a giant TV screen, so people can gather to watch the mass as it happens.
It means the service will be taking place simultaneously in piazzas all around the city.
Similar arrangements are being made in all Italy's major towns and cities, including Milan, Florence, Turin, Naples and Assisi.
So the "virtual" funeral will be a collective experience for millions across the country.
The Italian media is comparing the funeral of John Paul II to those of Gandhi, Stalin, John F Kennedy and Churchill, and saying this will be bigger than all of them.
Presiding over the funeral mass will be one of the late Pope's closest advisers, Cardinal Joseph Ratzinger.
The German-born cleric is Dean of the College of Cardinals, which makes him one of the key officials in the process to elect a new pope.
For most of the papacy of John Paul II he ran the Vatican department known as the Congregation of the Doctrine of the Faith. It is a direct descendant of the Inquisition of 1542.
Today, the department is responsible for doctrinal orthodoxy, and safeguarding the morals of the Catholic faithful.
It is a role that led to Cardinal Ratzinger becoming known as the Pope's "enforcer".
The service will last for three hours, and will take place in the presence of 200 invited guests, including world leaders and representatives of all faiths.
But there will be no opportunity for any of the dignitaries to make personal tributes, as the service will follow the traditional pattern of a requiem mass.
There will be readings from the gospels, a homily or sermon, and prayers for the Pope and the Church.
The Pope will be buried near the tomb of Pope John Paul I in the crypt
In accordance with Vatican tradition, John Paul II will be buried in a triple-lined coffin.
His body will first be placed in a simple coffin of cypress wood, to symbolise humility, and placed in front of St Peter's Basilica.
Before burial, it will be placed in a zinc coffin, hermetically sealed to slow down the process of decomposition. It will bear the name of the Pope and the dates of his pontificate.
This in turn will be placed in an oak coffin, before being interred beneath a marble slab.
The ceremony will take place in the crypt, deep beneath St Peter's Basilica.
The place chosen for John Paul II was previously used for Pope John XXIII, one of the Church's best-loved pontiffs.
The Polish Pope will lie close to the tombs of his two immediate predecessors, John Paul I and Paul VI, who both died in 1978.
In the days ahead, it will doubtless become a place of pilgrimage for Catholics unable to be present at the funeral.