Pope Leo is set to formally lead his first Regina Caeli prayers in St Peter's Square at the Vatican, as Supreme Pontiff of the Catholic Church. Thousands are expected to join him for the prayers. Yesterday, he made his first trip outside the Vatican, traveling about an hour east of Rome to visit a Catholic shrine. On the return journey, he stopped to pay his respects at the tomb of his predecessor, Pope Francis. Pope Leo was seen waving from the passenger seat of a Volkswagen vehicle as he arrived at Rome's St. Mary Major Basilica. Entering the church to a few shouts of "Long live the Pope," he walked slowly to the tomb of Francis and laid a white flower on it. He then knelt in prayer for a few moments. At the end of the visit, Pope Leo told those gathered at the shrine that he had come to pray for guidance in the early days of his papacy. Pope Leo XIV will be formally inaugurated at a Mass in St Peter's Square on May 18, with delegations from around the world expected to attend. The Duke of Edinburgh, Prince Edward, will represent King Charles, Buckingham Palace confirmed on Saturday.