Berlin remembers fall of the Wall
World leaders have hailed the fall of the Berlin Wall in celebrations marking the 20th anniversary of the upheaval that transformed Europe.
German Chancellor Angela Merkel was joined at the Brandenburg Gate by Russia's Dmitry Medvedev, France's Nicolas Sarkozy and UK PM Gordon Brown.
In a special video address, US President Barack Obama said Berliners on 9 November 1989 had rebuked tyranny.
The wall's fall led to Germany's reunification and the Cold War's end.
Communist East Germany erected the 155-km (96-mile) concrete barrier in 1961 to encircle West Berlin and prevent citizens from fleeing into the capitalist enclave.
There could be no clearer rebuke of tyranny, no stronger affirmation of freedom Barack Obama
At least 136 people are thought to have been killed at the wall while trying to escape. Ms Merkel, who grew up in East Germany, presided over Monday's celebrations.
She led a procession of leaders through the Brandenburg Gate - the symbol of German reunification in 1990.
The presidents of Russia and France, the British premier and US Secretary of State Hillary Clinton were among those who joined the German chancellor.
Ms Merkel said: "Freedom is… the most precious element of our political and social system. Without freedom there is no democracy."
Mrs Clinton also spoke, before introducing a surprise video address from Washington by Mr Obama.
"There could be no clearer rebuke of tyranny. There could be no stronger affirmation of freedom," he said of the wall's tearing down.
Mr Medvedev said the events of 20 years ago had helped Russia and Germany end their World War II enmity.
He said he hoped everyone had rejected the dividing lines represented by the wall. In his speech, Mr Brown told Berliners: "You dared to dream in the darkness. You knew that while force has the temporary power to dominate, it can never ultimately dictate."
Later, hundreds of giant foam dominoes - painted with messages of freedom by young people - that had been placed along the former route of the wall were toppled to reflect how the then Communist governments of Eastern Europe fell one after another.
Earlier in the day, the German chancellor retraced her steps on the night the wall fell by crossing what used to be the Bornholmer Strasse checkpoint, the first to open 20 years ago.
Ms Merkel was joined by ex-Soviet leader Mikhail Gorbachev and Lech Walesa, the former Polish trade union leader and later president, whose movement was the first to challenge Communist rule successfully in Eastern Europe.
There were cheers from hundreds of onlookers as Ms Merkel praised Mr Gorbachev for helping to make change possible.
Earlier, Ms Merkel said in a TV interview that German unity was still incomplete, as the East lagged in economic growth.
Former Hungarian Prime Minister Miklos Nemeth, whose decision to open his country's borders first allowed East Germans to flee to the West, also attended the celebrations.
The festivities were capped with fireworks and a concert featuring performances by musicians from across the world.