Germany is marking the 20th anniversary of its reunification with festivities and words of praise for the country's achievements since the merger of its former east and west.

German Chancellor Angela Merkel told German magazine Super illu that East Germans have done a tremendous job in adapting to the changes of the past 20 years.

U.S. President Barack Obama said German reunification was an historic achievement by one of America's closest allies and greatest friends. In a statement, he said it opened the door to unprecedented freedom throughout the European continent and globally.

Ms. Merkel said reunification turned daily life in her native east Germany completely inside out in every aspect, from shopping to bureaucracy and the working world.

She said the scarcity of goods during East Germany's communist rule caused her to stockpile food frequently, a habit she said has been hard for her to break.

The northwestern German city of Bremen is taking the lead in this year's celebration by hosting a street party with live music that began Saturday. The capital, Berlin, also is holding an entertainment program in front of the Brandenburg Gate.

Not all Germans were celebrating the occasion. Hundreds of leftists marched in Bremen against German nationalism Saturday as 3,000 police patrolled the city to prevent trouble. There were no major incidents.

Germany was divided into a communist east and capitalist west following the defeat of the Nazis in World War Two. The two sides merged on October 3rd, 1990, 11 months after peaceful protests in the east brought down its ailing communist government.

Unemployment in eastern Germany remains significantly higher than in the west, while wages remain lower, although the gap has narrowed in recent years.

Some easterners complain that westerners treat them like second class citizens, while some westerners complain about the high cost of reunification and feel easterners are ungrateful.