From The Washington Post:
Congressional leaders have invited Pope Francis to address a joint session of Congress during his expected visit to the United States next year.
Francis, who marked his first anniversary as leader of the world’s 1.2 billion Catholics today, is reportedly planning to visit the U.S. next year in order to attend a global conference on families scheduled for late September in Philadelphia. The Holy See has not confirmed the trip.
House Speaker John Boehner (R-Ohio), as the constitutional officer of Congress, made the formal invitation on behalf of House and Senate leaders, according to House and Senate aides. The House speaker is the officer who formally invites the president each year to give a State of the Union address. All joint sessions of Congress occur in the House Chamber because it is the larger of the two chambers.
Aides to Boehner said he sent the invitation Thursday to officials in Vatican City. If Francis accepts the invitation, he would be the first pontiff to ever address American lawmakers from the U.S. Capitol, according to Boehner aides.