Pope Francis is due to celebrate Easter Sunday Mass in St Peter’s Square in Rome on Sunday morning. The Mass, followed by the traditional “Urbi et Orbi” blessing – Latin for to the city and the world – is the solemn highlight of the Easter holidays and the most important festival in the Christian calendar. As in previous years, tens of thousands of people are expected to attend the celebration. However, the Vatican’s Easter festivities have been overshadowed by concerns about the 87-year-old pontiff, who has been in poor health for months. On Easter Sunday, Christians celebrate the resurrectio…