The history of the Berlin wall is fascinating. The wall itself … not so much. It’s just a concrete/wire mesh fence really. Not much to see.
What has surprised me the most about the Berlin wall, is how many people I know who don’t know anything about it. They know that it existed, but not why or how it came to be. If you are in that camp, then I recommend doing some reading up on the subject. I’m not going to attempt to explain it here myself, as there are others who are far more knowledgeable about such things than I and can explain it much better.