He also shook hands with Romans, who apparently had no idea who he is but figured he has to be somebody based on the pack of cameras following him.
The officials purpose of the trip is to plan for the World Meeting of Families, a once every three-year event started by Pope John Paul II.
Philadelphia will be the first U.S. city to host the gathering, which could bring more than 1 million people to the city if the pope decides to attend. Before stepping down, Pope Benedict XVI had said he planned to make the trip to Philadelphia.
Before departing Philadelphia on Sunday, Chaput said he hoped the pope would attend and added, "I can't imagine that he won't."
James J. Maguire, who leads the Maguire Foundation and is part of the World Meeting executive organizing committee, was optimistic the Vatican trip would be fruitful.
"We're going to meet the pope and encourage him to fulfill the previous pope's pledge to come visit Philadelphia," Maguire said as he and his wife joined a winding security line at Philadelphia International Airport.
President Obama also begins a European trip this week, including a meeting with the pope on Thursday.
The World Meeting of Families organized and paid for the Pennsylvania delegation's three-day trip to Rome. Nutter and Corbett are honorary co-chairs of the nonprofit, which is responsible for raising the substantial amount of money required to host the event.