.- For the first time, the Holy See's distinct white and yellow flag will fly alongside the flags of United Nation's countries in honor of Pope Francis' arrival to U.N. headquarters in New York City.

U.N. officials, after consulting with the Holy See, decided to raise the flag on the morning of Sept. 25 so that it will be flying when Pope Francis is scheduled to arrive at 8:30 a.m.

The Pope will then address a special summit to define the 2015 Sustainable Development Goals.

Both the Holy See and the U.N. Secretariats have agreed there will be no ceremony to accompany the flag raising, but it will be raised by U.N. personnel at the same time as the other flags that day.

The Holy See’s flag has two vertical bands of white and gold. The white side displays a pair of traversed keys, one gold and one silver, tied together with a red cord and topped by a triple-crowned miter with a cross sitting on its very top.

The image of the two keys holds a special significance in the Catholic Church, as they are linked to Jesus’ declaration to Peter in Matthew 16:19: “I will give you the keys of the kingdom of heaven; whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed.”

The keys are a traditional symbol of the papacy along with the miter. The keys are associated with Peter’s authority as head of the Church and vicar of Jesus Christ. The keys also signify St. Peter’s successors from the time of Peter’s death down to Pope Francis.

Although the Holy See is not an official member of the United Nations, it is one of two sovereign states that have observer status. Palestine is the other country with an observer mission.

In July 2004, the Holy See received all the rights of full membership except the right to vote. Interventions from the head of its permanent observer mission, Archbishop Bernard Auza, are frequent.

Pope Francis will address the U.N. special summit on the third day of his five-day visit to the U.S.

A small gathering greeted the Pope on his landing at Andrews Air Force Base in Washington, D.C. the evening of Sept. 22. He will meet with President Obama the next morning, and will canonize Bl. Junipero Serra at the National Shrine of the Immaculate Conception later that afternoon.

On Thursday Francis will be the first Pope in history to address a joint session of the U.S. Congress. The next day he will visit the U.N., after which he will hold a major interreligious encounter at Ground Zero, the site of the Sept. 11, 2001 terrorist attacks on the World Trade Center.

The Pope's visit will culminate with his visit to Philadelphia for the World Meeting of Families’ Sept. 27 concluding Mass. He will arrive back in Rome the morning of Sept. 28.