The East German government could stop people leaving East Germany.
The Wall showed that communist governments had to ‘imprison’ its people to ensure they stayed. At least 260 people died trying to escape.
Western leaders protested but there was little they could do.
In 1963, President John F Kennedy visited Berlin to reassure Berliners that the USA would not abandon them.
It was then he made his famous 'I am a Berliner' speech next to the Berlin Wall.
There are many people in the world who really don't understand what is the great issue between the free world and the communist world - let them come to Berlin!
There are some who say in Europe and elsewhere we can work with the communists - let them come to Berlin!
All free men, wherever they may live, are citizens of Berlin. And, therefore, as a free man, I take pride in the words 'Ich bin ein Berliner' ['I am a Berliner'].
The Wall remained until 1989.