Days after his inauguration, Pope Francis is set to return to a packed St Peter's Square for Palm Sunday Mass.
The Mass, which begins the start of Holy Week towards Easter, is set to be attended by thousands of pilgrims in Rome.
Yesterday, Pope Francis flew south of the city for an historic lunch meeting with his predecessor, Pope Emeritus Benedict.
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Accompanied by the Duke of Edinburgh, the Queen will attend the opening ceremony of the fifth session in the Holyrood chamber.
Ms Leadsom has received the backing of Ian Duncan Smith, the former work and pensions secretary.
The former shadow work and pensions secretary is considered a more viable candidate than Angela Eagle, a Labour source has told ITV News.