It is rare that a historical era can be defined with precision, but the fall of the Berlin Wall 20 years ago this week is just such a rarity. The breaching of that monstrosity marked the end of the Soviet empire and ushered in a era of both hope and considerable confusion. There is no mistaking the extraordinary significance of Nov. 9, 1989, but that vista is also a testimony to human failure. The world has been unable to construct a new vision and a new order. It is damning, indeed, that we continue to inhabit "the post-Cold War world."

The Berlin Wall appeared without warning Aug. 13, 1961. It was built by a communist government that ruled East Germany with violence, paranoia and repression. The wall was designed to halt the flow of migrants from East to West, a surge of humanity that sought to flee the Iron Curtain via a bolt hole hundreds of kilometers from the West. Eventually, the wall stretched nearly 150 km around the entire city of West Berlin, a concrete monstrosity dotted with barbed wire, 302 armed-guard towers, and numerous other means to keep East Berliners inside. While West Berlin became a symbol of freedom and hope, the wall, by contrast, was an equally powerful symbol of evil and fear, a symbol that was periodically bathed in blood: It is estimated that some 5,000 people tried to cross the wall; at least 136 people were killed in the effort.

But on Nov. 9, 1989, the symbol came crashing down. Following the opening of other Eastern European borders to the West — Hungary had taken that step in August and Czechoslovakia soon followed — the East German Politburo agreed to open its borders as well. The Politburo spokesperson had not been briefed on the decision and, when asked about details at a late-night news conference, said the order was effective "immediately." Berliners took him at his word and surged to the barrier. Thousands crossed both ways and border guards kept their weapons holstered. "Mauerspechte" (wall woodpeckers) took sledgehammers to it; the East German police tried halfheartedly to fix the damage, but on June 13, 1990, official efforts began to dismantle the barrier. German unification was concluded Oct. 3, 1990.