Pope Francis is to make his first visit to the Auschwitz death camp when he is in Poland for World Youth Day in July.
He will be the third Pope to visit the Auschwitz-Birkenau concentration camp where more than 1.5 million Jews were murdered or simply died of starvation in World War II. More than six million Jews overall were killed. Many Catholics, homosexuals and others were also slaughtered.
John Paul II, who was Polish, visited in 1979 when described it as the "Golgotha" of the modern world.
German-born Pope Benedict XVI visited in 2006 as "a son of the German people".
After praying, he said: "In a place like this, words fail. In the end there can only be a dread silence, which is a heartfelt cry to God. Why, Lord, did you remain silent? How could you tolerate all this?"