In the center of Berlin you find a big memorial for the murdered Jews during the Second World War. It is free to visit and you can just walk by from the Brandenburger Tor.
The Berlin Wall is mostly gone – but there are still a few sections left around the city. You can go and visit one right at the Nordbahnhof where there is also a small museum.
Close to the Brandenburger gate you will find a small Soviet war memorial from World War II. You can just walk five minutes down the street from the Brandenburger gate to get there.
Checkpoint Charlie was the most famous of the checkpoints between East and West Berlin during the cold war. It was here some of the most famous standoff between east and west took place.
At Nordbahnhof in Berlin you will find a small museum about how the subway system were run during the time of the Berlin Wall.