Germany on Sunday celebrated 20 years since reunification when the capitalist West and the communist East merged after decades of Cold War division that ended with the fall of the Berlin Wall.
Several hundred thousand people were expected in the northern city of Bremen for a series of street parties and official events led by Chancellor Angela Merkel, herself brought up in East Germany.
In a video podcast on the eve of the celebrations, Merkel paid tribute to East Germans for having "the courage to fight for freedom."
"At the same time, there was a huge wave of solidarity from the people in West Germany. It is thanks to these joint efforts that we have been able to rebuild so quickly and make Germany a country that is respected in the World."
Also expected to attend the reunification celebrations were European Commission President Jose Manuel Barroso and NATO Secretary General Anders Fogh Rasmussen.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
US President Barack Obama was quick to congratulate Germany, praising "the courage and conviction of the German people that brought down the Berlin Wall, ending decades of painful and artificial separation."
The peaceful reunification of East and West Germany was a "historic achievement," said the president.
After World War II, the victorious powers, the United States, Britain, France and the Soviet Union carved defeated Germany into four sections.
With the advent of the Cold War, Moscow erected a border between its eastern section and the three western Allied sections, including the Berlin Wall that split Berlin in two.
On October 3, 1990, just under a year after the wall was yanked down in a bloodless revolution, the reunification treaty bringing the two halves of the country together came into effect amid joyful scenes.
In a recent poll, 84 per cent of Germans said they believed national unification after four decades of division had been the right decision, despite a lingering economic gap between east and west.
Just 14 per cent said unity had been a mistake, according to the survey for ZDF public television.
While Germany has become a leading light on the international political stage and is Europe's top economy, the country is still battling to overcome yawning gaps between the west and the east that laboured under communism.
Unemployment remains nearly twice as high in the eastern states and living standards considerably lower, despite an estimated 1.3 trillion euros ($A1.83 trillion) in transfers from west to east.
And 20 years on, old stereotypes still run deep in German society, surveys suggest, with the Westerners ("Wessis") perceiving the Easterners ("Ossis") as ungrateful and Ossis believing Wessis to be arrogant.
There were some protests against the reunification festivities, with around 1,800 mainly left-wing activists conducting a march in Bremen on Saturday evening that passed off peacefully.
