Government spokesman Günter Schabowski told a press conference that East Germans could travel abroad. Asked when, he looked at his notes and said that, as far as he knew, it took effect immediately.
Thousands gathered at the checkpoints that night. At Bornholmer Strasse the guards, with no orders, opened the gates shortly before midnight. People climbed onto the wall and began breaking pieces off it. Germany was reunified less than a year later, on 3 October 1990.
Source: Wikipedia