Germany is marking 50 years since the communist East began building the Berlin Wall, which divided the city for 28 years.
On the morning of August 13, 1961, East Berliners woke to find armed soldiers had blocked off streets, cut off rail links, and begun building a wall of barbed wire and cemented paving stones. Over the years, the Wall grew in height and complexity and stretched to more than 155 kilometers.
Speaking at a commemoration of the bitter anniversary today, Berlin Mayor Klaus Wowereit said the wall must not be forgotten in reunified Germany.
"It is our shared responsibility to keep the memory alive and pass it on to coming generations as a reminder to stand up for freedom and democracy, to ensure that such injustice may never take place again," he said.
President Christian Wulff and Chancellor Angela Merkel, who grew up in East Germany, also attended the commemoration.
At least 136 would-be refugees are known to have died at the wall.
Commemorations began overnight at a chapel on the former death strip with a more than seven-hour-long reading about the lives of those killed seeking freedom in the West. The wall finally fell on November 9, 1989, in a bloodless uprising.
Only a few original sections of the Wall remain in place today, a reminder for some of the continuing economic division between the richer west and poorer east.
compiled from agency reports