Berlin — The Berlin Wall fell 25 years ago on Sunday, a key event in the collapse of communism and the preface to Germany's reunification in 1990.
The anniversary is being celebrated in Berlin with concerts, speeches and the release in the evening of thousands of balloons illuminating a 15-kilometer (nine-mile) stretch of the former Cold War barrier.
Here are five things to know about the Berlin Wall:
PROTECTION AGAINST 'FASCISM'
At 01:00 on August 13, 1961, East Germany sealed off the border between the Soviet-controlled eastern sector of Berlin and the western sectors controlled by the Allies.
Over the following weeks, workers erected a 155-kilometer barrier encircling West Berlin. The Wall itself — up to 3.6 meters high — was merely the outermost part of a heavily fortified strip that variously included barbed wire, metal fences, guard towers, hidden alarms and dog walkways.
Communist leader Walter Ulbricht called it an "anti-fascist protective wall," though in reality its purpose was to stop the flood of people leaving for the West.
Despite the formidable obstacle and threat of stiff punishment if caught, thousands of people tried to escape by tunneling under, swimming past, climbing or flying over the wall.
Many took advantage of Berlin's extensive sewer and subway network. Others used fake passports made out to West Germans, who were allowed to visit East Berlin.
Some dug their own tunnels, often with help from people on the other side. In one case, an entire family escaped using a home-made cable car.
WALL OF DEATH
At least 136 people, including several children, lost their lives along the Cold War barrier, according to the Potsdam Center for Historical Research.
Some were shot by East German border guards, others drowned in the chilly river Spree.
One of the last to die was Chris Gueffroy. The 20-year-old was shot dead nine months before the fall of the Wall.
Crosses now mark many of the locations where people died trying to reach freedom.
During its 28-year existence, the Wall served as a symbol for communist oppression.
Western leaders, including US President John F. Kennedy, often had a stop at the Wall when they visited Berlin.
The ominous, grey concrete barrier served as the backdrop for US President Ronald Reagan's call in 1987 to then-Soviet leader Mikhail Gorbachev to "tear down this wall!"
Gorbachev later claimed not to have taken the dramatic appeal seriously, calling it a "performance" by the one-time Hollywood actor. But the speech, like Kennedy's famous line about considering himself "a Berliner," helped keep up morale in the western part of the city.
On the evening of November 9, 1989, West German television broadcast the news that communist authorities had decided to lift travel restrictions and allow East Germans to travel more or less freely.
The reports were based on a confusing announcement by a senior East German official who had failed to spell out various caveats to the new policy. Before the communist authorities could set the record straight, thousands of East Berliners had pushed their way past perplexed border guards to celebrate freedom with their brethren in the West.
The communist dictatorship was swept away within months. On October 3, 1990, East and West Germany became one country again.