The Pope's body will be moved to St Peter's Basilica on Monday, where millions of mourners are expected to pay their respects to him.
It is estimated that up to two million people will visit the church to file past his body. His funeral is reported to take place on Friday morning.
Italian officials and important Vatican figures have already viewed his body, which is lying in state.
Cardinals are also due to meet soon to talk about who will replace the Pope.
Pope John Paul II was born in Poland and spent 26 years in the role of Pontiff, which makes him the third-longest running Pope in history.
Pope John Paul II died on Saturday 2 April 2005
He was very popular, and some people called him "the People's Pope". This is shown in the tens of thousands of people who have gathered outside the Vatican as a mark of respect.
John Paul II died on Saturday after a long illness, aged 84.
On Sunday, the Vatican issued the Pope's death certificate, saying he died from septic shock and irreversible heart failure.
Italy is to hold three days of mourning for the Pope
When the Pope's death was announced on Saturday evening the crowds in St Peter's Square gave a huge round of applause - which is an Italian sign of respect - before several minutes of silence.
British Prime Minister Tony Blair said John Paul "never wavered, never flinched, in the struggle for what he thought was good and right".
US President George Bush said: "The world has lost a champion of human freedom, and a good and faithful servant of God has been called home."
1. What is St Peter's Basilica?
2. Up to two million people will file past the Pope's open coffin? What do you think they will gain from viewing his body?
3. What does "lying in state" mean?
4. Why do you think Italian officials and important Vatican figures get to view his body first?
5. What will happen to the Pope's body now?
6. Why did the crowds in St Peter's Square give a huge round of applause when the Pope's death was announced?
7. What did the crowd do after the applause? Why do you think they did this?
8. Services of remembrance are taking place at Catholic churches throughout the world too. How does a memorial service help with grieving?
9. Why do people make memorials and tributes?