Walls never really did much for people's happiness have they? The Berlin Wall is a great example of something that didn't work.

The Berlin Wall lasted from 1961 to 1989 and aimed to prevent unhappy DDR citizens from moving to West Germany. The Wall was a source of political conflicts, it created a place where people would be threatened and shot by the border control and it isolated East Germany economically. The only access point in and out of East Germany was Checkpoint Charlie which separated the US-controlled area of West Germany and the Soviet controlled area of East Germany.

Like many walls In History and modern times, the Berlin Wall proved to be a very bad idea and a complete failure in achieving the goal of improving the economy of the Communist side of Germany by keeping their citizens inside and forbidding them to move abroad.

The idea of building walls in current times is still very much invoked and distributed for example during the Republican party campaign in 2016:

- https://www.youtube.com/watch?v=-yfIxBjOw3o

8 years later, the real problems related to immigration everywhere in the world are still being many times dealt with fear, anxiety, and almost always from a racist and nationalistic lens which can lead to very dangerous politics and the creation of unsafe societies. Walls have proven in the past to be great mistakes and they end up being removed at some point anyway.