Reason for building Berlin Wall
The main intention of The Berlin wall was to keep people within that country and not to go outside. For this, there was another reason for capitalism according to Soviets and East German Government. They said that West Germany refused to recognize East Germany as an independent country because they wanted to take over North-East Germany just like Hitler took over Poland.
Another intention was to keep western fascist away from getting an entry in East Germany and undermining the socialist state, but it primarily served the objective of stemming mass defections from East to West
Fall of the Berlin Wall: It was thanks to Soviet leader Mikhail Gorbachev that this symbol of division fell