Collecting Berlin's Underground

I might have told you: I am a collector - with my camera. I collect sun dials, balconies, shop window dummies, beautiful cars -- to name a few --- AND photos from impressing undergrounds. 
The first year in Berlin it was a bit difficult for husband: I always jumped up and down and cried: "Wait! Wait just a minute! I have to ..  click...click..." 
It is so utterly fascinating that they are so very, very different! As a true collector knows: one becomes boring offering too many snapshots -- so here only a few...