The conclave to elect a new pope begins on 7 May at 10am (AEST) with a public holy mass at St Peter’s Basilica.
The cardinals have already begun checking into hotels and are barred from the outside world as they decide who will succeed Pope Francis.
After the mass, the cardinals will head to the Sistine Chapel, where all cardinals under 80 will cast their first vote for who will be the new leader of the 1.4 billion-member church.
While some possible front-runners have been named, many of the 133 cardinals expected to vote said they don’t know who will be elected as the next pope.
This year’s conclave is also set to be the most geographically diverse in the church’s history with speakers from 70 countries.
The Conclave is likely to be spread out over multiple days, with the longest conclave lasting 1,006 days back in the 13th century. Recent conclaves have been shorter, lasting just two days in 2005 and 2013.
There are multiple rounds of voting and to be elected the contender must win two-thirds of the vote to become pope.
During the conclave period the voting cardinals will stay in two Vatican guesthouses and take an oath to remain out of contact with anyone not participating in the secret vote.
French Cardinal Jean-Paul Vesco said the estimated 400,000 people who attended Francis’ funeral and burial procession wanted a pope that shared the previous pope’s values.
“We need a pastor,” Vesco, the archbishop of Algiers, told the Corriere della Sera newspaper.
“At Francis’ funeral, this is what the people asked of us: give us a pastor.”
Related content
The conclave to elect a new pope starts today — here's what we can expect
