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Berlin celebrated the 20th anniversary of the fall of the Berlin Wall on Monday with symbolism, fireworks and concerts as current and former world leaders joined tens of thousands of people who marked the event. But amid much joy was also a note of caution.
A sea of umbrellas surrounded Berlin's Brandenburg Gate as tens of thousands of people braved the cold rain to join in the celebrations.
The reason for it all - 20 years ago, a series of peaceful revolutions and change broke down the massive gray wall that for nearly three decades divided Berlin, Germany and Europe with an Iron Curtain.
German Chancellor Angela Merkel described the fall of the Berlin Wall as the happiest day of her life.
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"We have every reason to celebrate today, to celebrate freedom," she said. The chancellor praised the courage of Germany's eastern neighbors who, with their peaceful uprisings, paved the way for freedom. And she thanked the Western allies for their staunch support throughout the Cold War.
Representatives from East and West were on hand - from former Soviet leader Mikhail Gorbachev and Polish labor leader and later president, Lech Walesa, to current Russian President Dmitri Medvedev, French President Nicolas Sarkozy and British Prime Minister Gordon Brown.
U.S. Secretary of State Hillary Clinton represented the United States and President Barrack Obama made a surprise video appearance.
"Like so many Americans, I'll never forget the images of people tearing down the Wall," said President Obama. "There could be no clearer rebuke of tyranny; there could be no stronger affirmation of freedom."
Amid praise and joy, German Chancellor Merkel spoke of another November 9, even longer ago that, she said, should always serve as a warning.
She said that 71 years ago, the pogroms of Adolph Hitler's Third Reich opened the darkest chapter in Germany's history - the systematic persecution and murder of Europe's Jews and many other minorities. "That too we do not forget today," she said.
On November 9, 1938, on Kristallnacht, or The Night of Broken Glass, at least 91 German Jews were killed and more than 200 synagogues were destroyed by rampaging Nazi mobs.
Chancellor Merkel said the Nazi pogroms and the Berlin Wall serve as reminders.
She said both show that freedom cannot grow and flourish on its own, "it has to be fought for and it must always be defended."
In a show of symbolism, a line of oversized, brightly painted dominoes had been set up across the Brandenburg Gate - running along an area where the Wall had once stood. On Monday night, the wall of dominoes fell, just as the Berlin Wall once did.
The crowd was full of young people and the message for them from past and present political leaders was that many walls - both physical and mental - remain to this day, walls and barriers to be broken down no matter where they exist.