Chancellor Angela Merkel hailed the courage of citizens 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, Ms Merkel is hosting dozens of world leaders, past and present, to remember the fall of the Wall.
"The night of November 9th, 1989, was the fulfillment of a dream," she said. "Many played a role. But it would not have been possible without the courage of the people in the former East Germany."
Mr 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.
Tonight, 1,000 brightly coloured dominoes set up along a 1.5 km stretch where the Wall once stood were toppled as world leaders watched 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-metre 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 US secretary of state Hillary Clinton - representing the World War Two allies - are all in Berlin to mark the event.
All the other leaders of the 27 European Union countries, including Taoiseach Brian Cowen, will also attend.
Backed by the Soviet Union, the East German government began erecting its "anti-fascist protection barrier" in the early hours of August 13th, 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 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 9th that East German citizens could leave through border crossings, effective immediately.
He was unaware that the decision was not supposed to be announced until 4.00am the next morning. Watched by thousands on television, it prompted a rush to the border that unprepared, overwhelmed 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," Ms Merkel said to Mr Gorbachev, who refused to order a crackdown. "You courageously let the things happen. That was much more than we could have expected."