Germany has been marking the 30th anniversary of the fall of the Berlin Wall with President Frank-Walter Steinmeier thanking Eastern European countries for making the peaceful revolution possible.
The breaching of the wall on November 9, 1989 followed a peaceful and popular uprising across communist East Germany amid moves among nations in Soviet-controlled Central Europe to break away from Moscow and shift towards western-style democracies.
It was followed a year later by the reunification of Germany in 1990.
"Together with our friends, we remember with deep gratitude the events 30 years ago," Steinmeier said during a ceremony at the Bernauer Strasse Berlin Wall Memorial, which was also attended by Chancellor Angela Merkel and heads of state from Poland, Hungary, Slovakia and the Czech Republic.
In August 1989, Hungarian border guards for the first time allowed people from East Germany to cross freely into Austria, paving the way for the fall of the Berlin Wall three months later and with it the end of the Iron Curtain.
Steinmeier said that today Germany and Europe faced fresh challenges.
"Liberal democracy is being challenged and questioned," Steinmeier said, adding that German and its European allies had to fight together for a "peaceful and united Europe."
His message was echoed by Merkel in a brief speech during a commemorative service at the memorial's chapel.
"The values on which Europe is founded -- freedom, democracy, equality, the rule of law, respect for human rights -- are anything but self-evident," she said, adding that such values "must be defended again and again."
Merkel commemorated those who were killed or imprisoned for trying to flee from East to West Germany and insisted that the fight for freedom worldwide isn't over.
"The Berlin Wall, ladies and gentlemen, is history and it teaches us: No wall that keeps people out and restricts freedom is so high or so wide that it can't be broken down," she said.
Merkel also recalled that November 9 remains a tragic date in German history, as it also marks the anniversary of the so-called Night of Broken Glass, an anti-Jewish pogrom in 1938 that foreshadowed the Nazi's Holocaust.