Pope Francis is underlining the price of war, visiting an American military cemetery and the site of a Nazi massacre in Rome.

Francis said the visits Thursday, which mark All Souls' Day, show that "wars produce nothing more than cemeteries and death. That is why I wanted to give this sign in a moment when our humanity seems not to have learned the lesson, or doesn't want to learn it."

The pope will first say Mass in the Sicily-Rome American Cemetery, where 7,680 American war dead who helped liberate southern and central Italy during World War II are buried and 3,095 missing are commemorated.

From there, the pope travels to the Ardeatine Caves, the site of one of the worst massacres of Nazi-occupied Rome.