The night of November 9 marks the 25th anniversary of one of the great turning points of modern history—the moment in 1989 when the Communist regime of East Germany finally collapsed, and the Wall that had cut Berlin in two since August 1961 at last came to be a meaningless strip of concrete. Border guards stood back, crossing points were opened, and ecstatic Berliners climbed on the top of the hated symbol to usher in a new world.

In the two days leading up to the anniversary on Sunday, Berlin will celebrate with thousands of illuminated balloons tethered along eight miles (12 kilometers) of the line of the Wall running through the center of the city.

At the anniversary moment itself, the