This weekend, Germany will observe the 25th anniversary of the fall of the Berlin Wall. The German Democratic Republic (East Germany) began erecting the barrier in 1961, building on existing checkpoints, and fortified it over nearly 30 years: The initial waist-high wooden gates gave way to massive concrete structures with buffer zones known as “death strips.” The Berlin Wall was intended to halt the steady stream of defections from the Eastern Bloc; during its existence, only about 5,000 people managed to cross over, escaping into West Berlin. More than 100 are believed to have been killed in the attempt, most shot by East German border guards. In 1989, waves of protest in East Berlin and a flood of defections through neighboring Hungary and Czechoslovakia led the government to finally allow free passage across the border. West German citizens swarmed the wall, pulling parts of it down with hammers and machinery, an act that set the stage for Germany’s reunification.