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.
Definitely take some time to walk around the mall. It's quite large, but I'd recommend heading over in the direction of the capitol, or going over to the Lincoln Memorial and Vietnam Memorial area.
There's nothing like strolling around the Mall when you're in a pensive mood. With the White House to the north, the Capitol to the east, and the Supreme Court just beyond that, you are truly in the center of the western world. It's a very powerful feeling.
It was cool. When the restaurant turns around, you can find notes on the window seal with a crayon, so grab it and say hello to the curious kid who left it there for you!
This is a vacation all by itself, one could spend months in here, Don't sit outside and lean on the glass pyramid, It is'nt allowed as we found out., even for a picture.