BERLIN (AP) - Thousands of cheering Germans re-enacted the electrifying moment the Berlin Wall came crashing down - toppling 1,000 graffiti-adorned 8-foot-tall dominoes that tumbled along the route of the now vanished Cold War icon, celebrating 20 years of freedom from separation and fear.

The spectacle - billed by organizers as a metaphor for the way the real wall came down 20 years ago Monday and the resulting fall of communist countries in eastern Europe - was one of several events to mark the anniversary and celebrate the profound change it had not only Germany, but Europe and the world.

Chancellor Angela Merkel - the first east German to hold the job - called the fall of the wall an "epic" moment in history.

"For me, it was one of the happiest moments of my life," Merkel said.

Yet she also recalled the tragic side of Nov. 9 for Germans - the Nazi’s Kristallnacht - or Night of Broken Glass - anti-Semitic pogrom 71 years ago. At least 91 German Jews were killed, hundreds of synagogues destroyed, and thousands of Jewish businesses vandalized and looted in the state-sanctioned riots that night.

"Both show that freedom is not self evident," Merkel said. "Freedom must be fought for. Freedom must be defended time and again. Freedom is the most valuable commodity in our political and social system."

Earlier, Merkel and former Soviet leader Mikhail Gorbachev crossed a former fortified border on Monday to cheers of "Gorby! Gorby!" as a throng of grateful Germans recalled the night 20 years ago that the Berlin Wall gave way to their desire for freedom and unity.

Within hours of a confused announcement on Nov. 9, 1989 that East Germany was lifting travel restrictions, hundreds of people streamed into the enclave that was West Berlin, marking a pivotal moment in the collapse of communism in Europe.

Merkel, who was one of thousands to cross that night, recalled that "before the joy of freedom came, many people suffered."