Crowds gather at Vatican Square
19 March 2013 Last updated at 07:07 GMT
Up to a million people are expected at the Vatican to attend the inauguration Mass for Pope Francis.
Political and religious leaders from around the world are also attending the Mass in St Peter's Square, marking the official start of his papacy.
The first pontiff from the Americas, he has suggested he will take a more modest approach than his predecessors.
Louisa Baldini reports from Vatican Square.