After lying in state for the past three days, Pope Francis's coffin will soon be removed from St Peter's Basilica and carried out to St Peter's Square - located just outside the front doors.
The funeral mass will be held outdoors, with heads of state and tens of thousands of mourners expected to gather in the public square.
The ceremony will begin at 10:00 local time (09:00 BST) and is expected to last for around an hour and a half.
After the mass has ended, Francis's body will be transported to the basilica of Santa Maria Maggiore in Rome for burial.
A nine-day mourning period will then begin.