President Joachim Gauck of Germany has visited a village in France, where 642 people were killed by Nazi troops in June 1944. The ruins of Oradour-sur-Glane are preserved just as they were after the massacre.
President Gauck said that he had accepted an invitation to visit the site with "gratitude and humility".
After World War II, General Charles de Gaulle ordered the village not to be rebuilt but instead remain a memorial to the evils of Nazi occupation. A new village was built nearby.
"I want to reach out to the victims and tell them: I am at your side," President Gauck, 73, told Europe 1 radio before the visit.
"I was born during the war, I was steeped in the discussion of our guilt,'' he said. ''I will tell the victims and their families: 'We know what was done.'"
The BBC reports he was joined in Oradour-sur-Glane by President Francois Hollande of France.
Together they visited the village square, where residents were rounded up by Nazi troops ostensibly to have their identity papers checked.
They also walked around a church where women and children were incarcerated before it was set on fire on 10 June 1944. The village's men were taken to a barn where they were shot with machine-guns.
The two presidents were accompanied by two of the three living survivors.
The BBC reports the reason for the massacre is unclear.
President Gauck has paid two other visits to the sites of Nazi mass killings in Europe - the Czech village of Lidice, near Prague, and the Italian hamlet of Sant'Anna di Stazzema in Tuscany.
In 1984, President Francois Mitterrand and former German Chancellor Helmut Kohl joined hands while attending a memorial service for fallen soldiers at the World War I battlefield of Verdun.