The Berlin Wall went up overnight in 1961. The two blocs of the Cold War — capitalist West and communist East — were separated by concrete in the middle of a city. Over the next 28 years at least 140 people trying to cross were killed by border guards. Families were cut off, the economy was severed; but the wall was the basic symbol of the Eastern Bloc's ability to stand.

In 1985 Mikhail Gorbachev came to power in the USSR; with glasnost (openness) and perestroika (restructuring) he relaxed the Soviet grip. The effect spread rapidly across Eastern Europe: in the summer of 1989 Hungary opened its border with Austria, and tens of thousands of East Germans escaped to the West via Hungary–Austria. The East German government tottered on the edge of collapse.

On the evening of 9 November 1989, East German spokesman Günter Schabowski was reading out new travel rules at a press conference when a journalist asked when they would take effect. Fumbling through his notes, he answered: "As far as I know… immediately, without delay." Western media broadcast this as "the border is open". Within hours tens of thousands of East Berliners streamed to the crossing points. Border guards had no clear orders; under the pressure of the crowd, they raised the barriers. By morning, thousands of people were dancing on top of the wall, chipping off pieces of concrete as souvenirs.

The physical dismantling of the wall continued over the following weeks and months. East Germany merged with the Federal Republic in 1990. The Soviet Union dissolved at the end of 1991. A seventy-year Cold War ended; a new phase of globalisation began. The fall of the Berlin Wall is one of the clearest turning points in the political calendar of the 20th century — the fall of a concrete object came to symbolise the fall of an abstract world order.