The Argentine-born pontiff made an early morning pilgrimage to the place where Adolf Hitler's forces killed more than 1 million people, most of them Jews, during World War II. Francis entered the camp on foot, walking slowly in his white robes beneath the notorious gate at Auschwitz that bears the cynical words "Arbeit Macht Frei (Work sets you free)."
After meeting briefly with 11 death camp survivors, he moved on to nearby Birkenau, a sprawling complex where people were murdered in factory-like fashion in its gas chambers. There he greeted 25 Holocaust rescuers.
Altogether, it was a deeply contemplative and private visit of nearly two hours that Francis passed in total silence, except for a few words he exchanged with the survivors and rescuers. Vatican and Polish church officials explained that Francis wanted to express his sorrow in silence at the site, mourning the victims in quiet prayer and meditation.
However, he did express his feelings, writing in the Auschwitz memorial's guest book in Spanish: "Lord, have mercy on your people! Lord, forgiveness for so much cruelty!" He then signed with his name in Latin, "Franciscus" and added the date "29.7.2016."
Francis is the first pope to visit Auschwitz who did not himself live himself through the brutality of World War II on Europe's soil. Both of his predecessors had a personal or historical connection to the site. St. John Paul II, born in Poland, witnessed the unspeakable suffering inflicted on his nation during the German occupation during the war. His successor, Pope Benedict XVI, who visited in 2006, was a German who served in the Hitler Youth for a time as a teenager.
Francis prayed silently for more than 15 minutes before greeting survivors, one by one, shaking their hands and kissing them on the cheeks. He then carried a large white candle to the Death Wall, where prisoners at Auschwitz were executed.
At the dark underground prison cell that once housed St. Maximilian Kolbe, a Polish friar who sacrificed his life to save that of a fellow prisoner who had a family, Francis prayed again. A few shafts from a tiny window were the only light cast on the pontiff.
He then traveled 2 miles (3 kilometers) to Birkenau, the vast satellite camp where the Nazis murdered Jews, Roma and others from across Europe. Invited guests, among them camp survivors and Christian Poles who saved Jews during the war, stood in respect as the pope arrived, his vehicle driving parallel to the rail tracks once used to transport victims to their deaths there.
At one point the deep silence was broken by the wailing of an infant. When Francis arrived, the hundreds of guests applauded. Francis slowly observed each of the memorial plaques in the 23 languages used by the inmates.
Poland's chief rabbi, Michael Schudrich, then recited, in Hebrew, Psalm 130, which starts: "From the depths I have cried out to you, O Lord." Francis clasped his hands and bent his head as the psalm was read, first by the rabbi and then by a priest in Polish.
John Paul's visit to the site in 1979 made history because it was the first ever by a pontiff, part of the Vatican's historical efforts at reconciliation with Jews. As a pope hailing from another continent, Francis's presence highlights visit the universal importance of a site that in recent years has drawn ever more visitors from around the world. The millions who now visit have put increasing stress on the site's aging barracks, prompting urgent conservation efforts that are being funded by governments worldwide.
Francis' visit is also different in that it had a private character with no speeches. Benedict, for instance, spoke there in 2006 in Italian — pointedly avoiding his native German language — in a speech questioning why God was silent at the slaughter of so many.
The pope's visit to Auschwitz came on the third day of a five-day visit to Poland that includes meetings with young pilgrims taking part in World Youth Day, a global celebration of faith. Friday is devoted to the theme of suffering. Later in the day Francis will visit a children's hospital in Krakow and take part in a Way of the Cross with the young people.
Gera reported from Warsaw. Monika Scislowska in Krakow contributed to this report.
Frances D'Emilio is on twitter at www.twitter/fdemilio.