In a visit of high ecumenical significance, King Charles III and Queen Camilla will make a state visit to the Holy See from Oct. 22-23. Pope Leo XIV will receive them in a private audience in the Vatican’s Apostolic Palace on Oct. 23, and afterward, for the first time, a British monarch and a pope will pray together in the Sistine Chapel.

King Charles wanted to make this state visit during the Jubilee Year 2025, and it had originally been scheduled to take place last April but had to be postponed due to Pope Francis’ illness. The royal couple was granted a private meeting with Francis during his convalescence, on April 9, the 20th anniversary of their wedding. Pope Francis died two weeks later, and the visit was rescheduled for this coming week.

It will be the king and queen’s first meeting with Pope Leo and will take place at 11 a.m. on Thursday, Oct. 23, in the private library of the Apostolic Palace. Afterward, the king will have a meeting with Cardinal Pietro Parolin, the Vatican secretary of state, while the queen will visit the Pauline chapel in the Apostolic Palace.

Then, just after midday, the king and the pontiff will make history by praying together in an ecumenical service in the Sistine Chapel, where Leo was elected pope on May 8. The service is seen as an important sign of reconciliation, the first of its kind since the separation of the churches of England and Rome in the 16th century.

As king, Charles is the supreme governor of the Church of England and will be accompanied on the visit by the Anglican archbishop of York, Stephen Cottrell, since Archbishop Sarah Mullally, the newly appointed archbishop of Canterbury, will not be installed until 2026. Archbishop Contrell will participate in the prayer service in the Sistine Chapel together with the moderator of the general assembly of the Church of Scotland, Rosie Frew, and Cardinal Vincent Nichols, the archbishop of Westminster.

The singing at the prayer service will be led by the children’s choir of the Chapel Royal of St. James’ Palace, the adult choir of St. George’s Chapel, Windsor Castle, and the Sistine Chapel Choir. The prayer service will focus on care for God’s creation, something that Charles has been passionately committed to long before becoming king.

After praying in the Sistine Chapel, King Charles and Pope Leo will go to the Sala Regia, a state hall in the Apostolic Palace next to the Sistine Chapel, for an about half-hour discussion on care for creation. There, they will be joined by representatives from the business world committed to sustainable development, as well as religious and civil society engaged in the care for the environment.

The royal couple will then leave the Vatican and, in the afternoon, drive to the papal basilica of St. Paul’s Outside the Walls, which is attached to a Benedictine abbey, for another ecumenical ceremony. The basilica and abbey have centuries-old links to the English monarchy, dating back to the Saxon kings who contributed to the upkeep of these ancient buildings. By the late Middle Ages, the kings of England were regarded as the protectors of the basilica and abbey, as recalled by the insignia of the Order of the Garter that can be seen there today.

The archpriest of the basilica, Cardinal James Harvey, and the Abbot of St. Paul’s, Donato Ogliari, O.S.B., will welcome the king and queen on their arrival, escort them through the Holy Door into the basilica and take them to the tomb of St. Paul, under the main altar.

There, in the basilica, King Charles will be given a unique honor, with the approval of Pope Leo. He will be officially welcomed as a “Royal Confrater” (royal fellow-brother) of the basilica and the abbey, as a gesture of hospitality and spiritual fellowship, reflecting the deep friendship between the Roman Catholic Church and the Church of England. He will also be given a special chair that is decorated with his royal coat of arms and the motto “Ut Unum Sint” (“That they may be one”)—words from Chapter 17 of St. John’s Gospel that Pope John Paul II chose to title his encyclical on ecumenism. He will sit on this chair during the singing of vespers, and the chair will remain in the basilica after the ceremony.

It is indeed appropriate that all this will take place in St. Paul’s Basilica, where Pope John XXIII announced the convocation of the Second Vatican Council on Jan. 25, 1959, on the Feast of the Conversion of St. Paul. Here, too, Pope Paul VI and Archbishop Michael Ramsey of Canterbury prayed together on March 24, 1966, and announced the establishment of an official dialogue between the Roman Catholic Church and the Anglican Communion that has borne much fruit over the past half-century. On that occasion, the pope gave the archbishop his own pastoral ring, a ring that, since then, the archbishops of Canterbury have worn on visits to the pope and at major ecumenical events. Since Vatican II, St. Paul’s has also become the site of major ecumenical events every year.

After the singing of vespers and the public recognition of Charles as a “Royal Confrater,” the king and queen will drive to the nearby Beda College, a Catholic seminary (named for St. Bede, the English saint and scholar) for men who discern their vocations late in life. There, a reception will be hosted for the royal couple, with invited guests.

That is the last major event of the state visit to the Holy See before they return to England.

King Charles has made at least five visits to the Vatican and met St. John Paul II, Pope Benedict XVI and Pope Francis. The royal couple previously met Pope Francis on a visit to the Vatican on April 4, 2017. King Charles, then the Prince of Wales, also met Pope Francis on Oct. 13, 2019, at the canonization of St. John Henry Newman. Pope Leo will be the fourth pope to meet with Charles.

Gerard O’Connell is America’s senior Vatican correspondent and author of The Election of Pope Francis: An Inside Story of the Conclave That Changed History. He has been covering the Vatican since 1985.