Catholic cardinals will sequester themselves behind the Vatican's medieval walls for the start of a conclave to elect the 267th pontiff of the Roman Catholic Church, a successor to Pope Francis who died in April at the age of 88.

The Sistine Chapel was decked out to host a papal election Tuesday as cardinals from around the globe moved into a Vatican guest house ahead of the conclave to choose Pope Francis's successor.

When the conclave begins in the Sistine Chapel on Wednesday, everything will revolve around the successor to pope Francis. The focus will be on the cardinals, including some who are not considered candidates and are less well-known.

In total, 133 cardinals will be voting during this conclave, the most electors ever, with 108 of them being appointed by Pope Francis.

Cardinals who will take part in the secret conclave to elect a new Catholic pope began checking into two Vatican hotels on Tuesday, where they will be barred from contact with the outside world as they decide who should succeed Pope Francis.