CELEBRATIONS, remembrances and joyful exuberance enveloped Germany today, the 20th anniversary of the night the Berlin Wall came down, a momentous event that helped transform Europe and signaled the beginning of the end of communism on the continent.

Led by Chancellor Angela Merkel and featuring a panoply of European, US and Russian leaders - current and former - Germany and its citizens were set to celebrate the historical watershed with concerts by Bon Jovi and Beethoven.

There will also be memorials to the 136 lives lost of those who tried to cross the nearly 100-mile (155-kilometer) long barrier that vivisected Berlin in two and stood as the most visible reminder of what was then an intractable, seemingly endless Cold War between the West and East.

US Secretary of State Hilary Clinton said yesterday that "the ideals that drove Berliners to tear down that wall are no less relevant today. The freedoms championed then are no less precious."

Today "should be a call to action not just a commemoration of past actions," she said.

Several leaders are coming to Berlin to take part in ceremonies, including the heads of state of all 27 EU members, Russian President Dmitri Medvedev and Clinton who, on behalf of the American people, accepted the Atlantic Council's Freedom Prize, a nod to the long presence of US troops and support for West Germany from the Berlin Airlift of the late 1940s to visits by President John F. Kennedy and Ronald Reagan.

Berlin Mayor Klaus Wowereit said that Kennedy had "encouraged and inspired the people of Berlin when he stood before the Schoeneberg town hall in 1963 and said 'All free men, wherever they may live, are citizens of Berlin. And, therefore, as a freeman, I take pride in the words 'Ich bin ein Berliner.'"

An estimated 100,000 people were expected to gather tonight in front of the Brandenburg Gate, the iconic gateway that once stood in the midst of no man's land, surrounded by the wall, barbed wire and machine guns.

Instead of border guards and tense emotion, the gate will be site of music, speeches and fireworks, harkening back to the night of Nov. 9, 1989, when people danced atop the Berlin Wall, feet thudding on the cold concrete, arms raised in victory, hands clasped in friendship and giddy hope.

On that cold night, years of separation and anxiety melted into the unbelievable reality of freedom and a future without border guards, secret police, informers and rigid communist control.

Elsewhere in the city, Germans will remember the 136 people killed trying to cross over from 1961 to 1989; hold candle lightings and with 1,000 towering plastic foam dominoes to be placed along the wall's route and tipped over.

On Nov. 9, 1989, East Germans came in droves, riding their sputtering Trabants, motorcycles and rickety bicycles. Hundreds, then thousands, then hundreds of thousands crossed over the following days.

Stores in West Berlin stayed open late and banks gave out 100 Deutschemarks in "welcome money," then worth about $50, to each East German visitor.

The party lasted four days and by Nov. 12 more than 3 million of East Germany's 16.6 million people had visited, nearly a third of them to West Berlin, the rest through gates opening up along the rest of the fenced, mined frontier that cut their country in two.

Sections of the nearly 155 kilometers (100 miles) of wall were pulled down and knocked over. Tourists chiseled off chunks to keep as souvenirs. Tearful families reunited. Bars gave out free drinks. Strangers kissed and toasted each other with champagne.

Klaus-Hubert Fugger, a student at the Free University in West Berlin, was having drinks at a pub when people began coming "who looked a bit different."

Customers bought the visitors round after round. By midnight, instead of going home, Fugger and three others took a taxi to the Brandenburg Gate and scaled the 12-foot (nearly four meter) wall with hundreds of others.

"There were really like a lot of scenes, like people crying, because they couldn't get the situation," said Fugger, now 43. "A lot of people came with bottles" of champagne and sweet German sparkling wine.

The wall the communists built at the height of the Cold War and which stood for 28 years is mostly gone. Some parts still stand, at an outdoor art gallery or as part of an open-air museum. Its route through the city is now streets, shopping centers, apartment houses. The only reminder of it are a series of inlaid bricks that trace its path.

Checkpoint Charlie, the prefab that was long the symbol of the Allied presence and of Cold War tension, has been moved to a museum in western Berlin.

Potsdamer Platz, the vibrant square that was destroyed during World War II and became a no man's land during the Cold War, is full of shops selling everything from iPods to grilled bratwursts.

In an interview in Moscow with Associated Press Television News, former Soviet leader Mikhail Gorbachev said the collapse was a catalyst for peace.

"No matter how hard it was, we worked, we found mutual understanding and we moved forward. We started cutting down nuclear weapons, scaling down the armed forces in Europe and resolving other issues," he said.

It all began with a routine late afternoon news conference.

On Nov. 9, 1989, Guenter Schabowski, a member of East Germany's ruling Politburo, casually declared that East Germans would be free to travel to the West immediately.

Later, he tried to clarify his comments and said the new rules would take hold at midnight, but events moved faster as the word spread.

At a remote crossing in Berlin's south, Annemarie Reffert and her 15-year-old daughter made history by becoming the first East Germans to cross the border.

Reffert, now 66, remembers the East German soldiers being at a loss when she tried to cross the border.

"I argued that Schabowski said we were allowed to go over," she said. The border soldiers relented. A customs official was astonished that she had no luggage.

"All we wanted was to see if we really could travel," Reffert said.