The pope travelled to Auschwitz, located some 70 km from the southern city of Krakow, on Friday morning, Radio Poland reported.
The pope had in June announced that he would not deliver an address at the Auschwitz camp.
Talking to reporters, the pontiff said at the time that he wanted to go to that "place of horror" with a minimal entourage. "May the Lord give me the grace of crying," the pope added.
Auschwitz was part of the itinerary of Polish-born Pope John Paul II's first pilgrimage to his homeland, on June 7, 1979, and of the pilgrimage of Pope Benedict XVI on June 28, 2006. Both them delivered homilies at the site.
Read alsoPope: World is at war but it's not a war of religions but for powerFriday marks the 75th anniversary since Polish Franciscan monk Father Maksymilian Kolbe, imprisoned at the camp, volunteered to give his life for another inmate, who had a wife and children.
After two weeks in a starvation cell, Father Kolbe was given a lethal injection of carbolic acid. He was canonized in 1982. Pope Francis is to pray in silence in Father Kolbe's cell, at the Wall of Death and at a memorial commemorating the over one million victims of Auschwitz.
