WEIMAR, Germany — President Barack Obama, the first U.S. president to visit Buchenwald, walked through the former Nazi concentration camp with someone very familiar with its history: Holocaust survivor Elie Wiesel.

Obama invited the Nobel Peace Prize winner to join him Friday for a somber tour of the site where 56,000 people died during the Holocaust. Many of them were Jews, including Wiesel's father.

"Memory must bring people together rather than set them apart," said Wiesel, who flew to the former camp on Obama's presidential helicopter.

"What else can we do, except invoke that memory so that people everywhere can say the 21st century is a century of new beginnings filled with promise and infinite hope and, at times, profound gratitude to all those who believe in our task, which is to improve the human condition?"

Wiesel and his family were deported from what is now Romania to Auschwitz, another concentration camp where his mother and younger sister died. He was then moved to Buchenwald, where his father died three months before the camp was liberated in 1945.

The visit also had personal significance for Obama: a great-uncle helped liberate a nearby satellite camp, Ohrdruf, days before other U.S. Army units overran Buchenwald.