I heard that they originally built it as a fence in on night

Yes, it was a very good wall.

It demonstrated quite well the fact that there is something wrong with a system when the hierarchy has to build a wall to keep its citizens in.

There's something just as wrong about a system so terrified of its neighbors that it wants to build a wall to keep them out--even though their ancestors were living on that continent long before the people who want the wall did. Even though those same people who want the wall also want to be able to travel freely to that country to sample its many pleasures.

And the Berlin Wall demonstrates something else--walls always fail in the end. Other examples--The Great Wall of China--Masada--The Alamo--The Maginot Line--The Siegfried Line--last Sunday's episode of The Walking Dead.