Pope Francis participates in an inter-religious gathering at the location of Ground Zero in New York City on Sept. 25, 2015 during the Holy Father’s apostolic journey to the United States.

Crowds gathered outside of Independence Hall in Philadelphia on Sept. 27, 2015 to hear Pope Francis speak about religious liberty during his apostolic visit to the United States for the World Meeting of Families.

Pope Francis meets with U.S. President Barack Obama and the First Lady at the White House for a welcoming ceremony on Sept. 23, 2015.

The welcoming ceremony at the White House for Pope Francis during his meeting with U.S. President Barack Obama on Sept. 23, 2015.

Pope Francis made a surprise visit to the Little Sisters of the Poor in Washington, D.C. on Sept. 23, 2015.

Pope Francis celebrates Mass at Madison Square Garden in New York on Sept. 25, 2015 during the Holy Father’s apostolic journey to the United States.

Pope Francis speaks to the United Nations General Assembly in New York City about caring for the environment and the human person on Sept. 25, 2015 during the Holy Father’s apostolic journey to the United States.

Pope Francis meets with U.S. Bishops in St. Matthew’s Cathedral in Washington, D.C. on Sept. 23, 2015.

Pope Francis arrives at the Basilica of the National Shrine of the Immaculate Conception on the occasion of the canonization of Bl. Junipero Serra.

Pope Francis celebrates Mass at the Basilica of the National Shrine of the Immaculate Conception on the occasion of the canonization of Bl. Junipero Serra, a Spanish-born Franciscan friar known for starting nine Spanish missions in California in the 1700s.