Massive lines at some security checkpoints ahead of Mass

CENTER CITY (WPVI) -- Massive crowds have formed at some security checkpoints as pilgrims try to reach the Ben Franklin Parkway and surrounding area to see the papal Mass.

To help alleviate crowds, the security checkpoint at 20th & Callowhill Streets, which was previously reserved for ticketed guests only, began accepting both general public and ticketed guests to alleviate lines for the security checkpoint at 19th & Wood Streets.

People are waiting for hours to get through some checkpoints, and photos show lines going back many blocks.

An estimated 1 million people are expected to be in attendance.