Near the Brandenburger Tor you will see a Starbucks. From there the Free Berlin Tours take place. http://www.newberlintours.com/ They also offer a few others. I took that and the alternative Berlin tour which was great.
The Reichstag. One of my favorite travel memories took place here in November, 2003. Nowadays you have to register in advance to visit this historic building. I've made my registration and even reserved a time for dinner at the top.
I prefer California - just sayin'. EXCEPT, it's great to be able to have a beer or coconut water for $1 at a kiosk right on the beach. The sidewalk is kinda awesome too.
This place gives me chills; the scale of it is just breathtaking. When you're here make sure to press your heel into the bull's private parts--you'll see when you get there. ;)