BERLIN - Chancellor Angela Merkel hailed the courage of easterners who helped bring down the Berlin Wall as the city celebrated the 20th anniversary of the events that marked the end of the Cold War and the beginning of a reunited Germany.

The first chancellor to have grown up in communist east Germany, Merkel is hosting dozens of world leaders, past and present, to remember the fall of the Wall.

The night of November 9, 1989, was the fulfillment of a dream, Merkel said. Many played a role. But it would not have been possible without the courage of the people in the former East Germany.

Merkel took a walk with former Soviet premier Mikhail Gorbachev and former Polish leader Lech Walesa across the bridge at Bornholmer Strasse where East Berliners first breached the border two decades ago in an emotional rush to freedom.

Later Monday, 1,000 brightly colored dominoes set up along a 1.5 km (0.9 mile) stretch where the Wall once stood will be toppled as world leaders watch from the Brandenburg Gate, once a symbol of division and now the signature image of a reunited Germany.

Images of the historic night when easterners trapped behind the 3.6-meter (12-foot) high concrete barrier crowded into checkpoints have dominated German television and newspaper coverage for the past week.

British Prime Minister Gordon Brown, French President Nicolas Sarkozy, Russian President Dmitry Medvedev and U.S. Secretary of State Hillary Clinton -- representing the World War Two allies -- are all in town to give speeches.

In pre-released excerpts of his Monday evening remarks, Brown hailed the unbreakable spirit of men and women who dared to dream in the darkness.

Sarkozy put a picture of himself on social networking site Facebook that he said showed him hammering away at the Wall on the fateful night.

It was a night full of enthusiasm: the German people reuniting marked the end of the Cold War and the start of a period of great freedom in Europe, he wrote.

DEADLY BARRIER

Backed by the Soviet Union, the East German government began erecting its anti-fascist protection barrier in the early hours of August 13, 1961, to end a mass flight of its citizens into capitalist West Berlin.

Initially a makeshift fence of barbed wire, it was gradually built up into an imposing 156-km (97-mile) barrier that encircled the three western sectors of the city and was patrolled by guards who were ordered to shoot anyone who tried to escape.

According to a study published this year, at least 136 people were killed at the Berlin Wall between 1961 and 1989 while trying to flee.

Thousands of others managed to evade the minefields, guard dogs and watchtowers, using schemes including tunnels, aerial wires and hidden compartments in cars to make it to the West.

The Wall fell after Politburo spokesman Guenter Schabowski told a news conference on November 9 that East German citizens could leave through border crossings, effective immediately.

He was unaware that the decision was not supposed to be announced until 4 a.m. the next morning. Watched by thousands on television, it prompted a rush to the border that unprepared, overwhelmed eastern guards were unable to contain.

Not a single shot was fired and the night turned into a giant city-wide party with easterners roaming the streets of West Berlin in disbelief and residents from both sides of the Wall embracing each other impulsively.

You made this all possible, Merkel said to Gorbachev, who refused to order a crackdown. You courageously let the things happen. That was much more than we could have expected.

Helmut Kohl, chancellor when the Wall fell, promised easterners flourishing landscapes when the two Germanys unified a year later.

But despite an estimated 1.3 trillion euros in transfers to rebuild the East, the so-called new states still suffer from unemployment rates twice that of the West.

A poll of over 1,000 Germans for the Leipziger Volkszeitung daily showed one in eight wanted the Wall rebuilt -- with the numbers nearly equal in East and West.

(Writing by Noah Barkin; Editing by Sonya Hepinstall)

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