Had breakfast now we must decided...

Dad and I are current in Frankfurt, Germany.  People are in quite a rush here! English is spoken much less than it has been all day. 

We are waiting for our last flight of the day.   And deciding what to see in Berlin? Suggestions anyone!? I said that I want to go see a concentration camp.  They are however a big time comment and we only have a day and a half.   

Any suggestions are more than welcome!