As he gets set for his first visit to Japan as pontiff, one city sits on top of Pope Francis' list of places to visit.

"Nagasaki is the place the pope wants to visit foremost," said a Vatican source about the pope's visit, which begins Saturday. That's why the southwestern city is at the start of his tight itinerary, the source added.

A top priority for the 82-year-old pope in Nagasaki, home to many of the country's Christians, will be to express his sorrow over those who lived and died for their faith during the Sengoku, Azuchi-Momoyama and Edo periods.