Only been there for one afternoon, so not a great authority, but: - Brandenburg gate is the obvious photo opportunity - Checkpoint Charlie is quite famous, but apparently not all that (not been there) - I found the holocaust memorial well worth a visit - The view from the TV Tower is supposed to be quite impressive - Kaufhaus der Westen (KdW) is a famous department store - If she's there for a while and it's her sort of thing, she could get the train to Oranienburg (about 30 minutes) and go to the Sachsenhausen concentration camp That's all stuff that you could get from a guide book though. Not sure if that's any help?
Google tells me Magdeburg has the highest average age in Germany. Can't say I've heard of it before but I know where @Red Hadron Collider is vacationing next.