The Berlin Wall did not run a straight course, as seen in this picture. Most of the wall has come down since 1989, but there are parts of it which remain, as a reminder. Sections of the city have just a row of stones in the ground with a marker noting where the wall had been.
Mauer Park (Wall Park) has a broad boulevard called Mauer Weg which now serves as a pedestrian/bike way.
One evening we wandered over to the Gedenkstätte Berliner Mauer, the Berlin Wall Memorial, which runs just over a km long with many explanatory signs along the way. Here an enitre cemetery had to be moved as the wall was slated to run right through the middle of it. A row of apartment buildings abutted the border, and just after the wall was built, people jumped out of their windows to the west side (while people below caught them).
In another part of the city, the East Side Gallery is also a section of wall that is over 1 km long, the west side of which has been painted by 101 commissioned artists. Some of these paintings are fairly famous. Unfortunately, many people have graffitied over the art. Not only that, but sections of the wall are crumbling. There is a society that is trying to preserve this monument.