In a historic moment, King Charles and Pope Leo are set to pray together at a church service in the Sistine Chapel on Tuesday, marking the first time a British monarch and pope have done so since the Reformation in the 16th century.

The service will bring together clergy and choirs from the Roman Catholic Church and the Church of England, over which the King serves as Supreme Governor.

During their state visit, King Charles and Queen Camilla will also visit Rome’s Basilica of St. Paul Outside the Walls, one of Catholicism’s four most venerated churches.

Pope Leo will grant King Charles a new title of “Royal Confrater,” or brother, at the connected abbey.

“This is certainly an historic event,” said Archbishop Flavio Pace, a senior Vatican official responsible for ecumenical dialogue. “It is the recognition of a joint journey” among the two Churches.

The Catholic Church and the Anglican Communion have been improving their ties since the 1960s, but this visit represents some of the strongest steps of recognition yet taken between the denominations.

Although the teachings of the two traditions align on many major issues, differences remain, such as the Catholic Church’s stance on ordaining women and priestly marriage.

As part of the visit, King Charles will receive a special seat in the apse of the Rome basilica, decorated with the king’s coat of arms and the ecumenical motto “Ut unum sint” (That they may be one). The wooden chair is reserved for future use by British monarchs.

The King and Pope Leo will also discuss climate sustainability issues during their meeting after the service.

Historic Meeting King Charles and Pope Leo will pray together in the Sistine Chapel, marking the first time a British monarch and pope have done so since the Reformation.

The visit aims to strengthen ties between the Catholic Church and the Church of England.

Pope Leo will grant King Charles the title of “Royal Confrater,” or brother.