Because they didn't want anyone to try to escape over it.
The Berlin Wall was patrolled by soldiers on the East German side and they had orders to fire on people trying to climb over the wall to West Berlin.
It was built to keep the people in. Berlin was until the Wall was built, a popular place for East Germans to elope to the West. The wall divided Berlin in that by crossing over it, or tunneling under it, people of East Germany could escape into the 1/2 of the city governed by France Great Britain and the US.
The people tried to escape by tunnels, roping over, hot air balloons, smashing cars through barbed wire, and probably more.
On August 15, 1961, Conrad Schumann was the first East German border guard to escape by jumping the barbed wire to West Berlin
It is estimated that around 5,000 people attempted to escape over the Berlin Wall during its existence from 1961 to 1989. Of those attempts, approximately 3,000 were successful, while hundreds of others were caught or killed. This means that a small percentage of East Berlin's population actually undertook the perilous journey to escape, highlighting the desperation of many to seek freedom. Overall, the percentage of individuals who attempted to escape is difficult to pinpoint precisely due to the secretive nature of such actions.
The residents of Berlin, Germany, were not specifically fighting over the Berlin Wall. The Wall represented the separation of East Germany (under the control of communism) from West Germany (under a less oppressive government). Residents from East Germany were forbidden by their government from fleeing to West Germany, and thus those who valued freedom - in both the East and West - fought to bring down the Berlin Wall and reunite Germany as one nation.
Defection, in politics, is when people illegally move out of a communist country. It applies to the Berlin Wall because quite a few people defected over, under, through or around it, and because the Wall was built to keep people from doing that.
They were worried that the people would try to escape over to West Germany. That's why soldiers were posted to shoot anyone who dared to come around. The communists wanted to keep their power over East Germany safe.
The Berlin Airlift took place all over Europe, where allied planes flew supplies over Soviet terrain to supply the people of Berlin, Germany!
Yes - shot, killed by land mines, trip wires attached to explosives, beaten to death. At least 125, perhaps as many as 500, people were killed trying to escape.
The Berlin Wall was made of cement, so they don't buy bricks. It is a piece of history and it was a symbol of communism and repression for over 50 years. The night that the first hole was made was one of celebration and freedom. As a child I saw pictures and heard stories of people trying to escape under or over the wall to freedom from East Germany. Families were kept apart for years because they happened to be on one side of the wall or the other. To have a bit of history of something like this reminds people that things can change and that there is always hope.