I've always loved history since I was little. Ancient history that is. The closer an event comes to present times, the less interesting I find it to be. Therefore, when it came time to study World War II in high school, I could hardly even feign interest.
Fast forward and I'm standing in Berlin. Suddenly I'm surrounded by all these places mentioned in my history books that I let slip out of my memory. And, while it was easy for me to try to forget about these events before coming to Berlin, the German had to live on a day to day basis, remembering the atrocities their country had committed, constantly surrounded by memories of the past. It would have been easy to simply bulldoze all those memories- destroy them and cover them up with new buildings that didn't harbor such pain. But instead the Germans acknowledge their past.
The Memorial to the Murdered Jews of Europe, Bebelplatz, Memorial for the Victims of War and Tyranny and even the Parliament building are all examples of structures around Berlin that one should visit to better understand its history and learn this lesson: don't forget your past or you will repeat it. Germany committed some horrible acts during World War II but instead of denying their past, covering it and smilingly warmly at tourists, they admit their faults. This acknowledgement is what enables them to move forward, strive to do better, and create a new era in German history.