Hi Catherine

My great-grandfather is also from Danzig, so this was interesting to me.

I found this web site where it shows in Zoppot, Cecilienstrasse = Czyżewskiego  http://www.danzig-online.pl/nazwy/uliced.html

 

If you can find an old map online  from the era you are searching and compare it to a modern Polish map, you can see where it is .
If you Google Cecilien Strasse Danzig you get a lot of results.

This worked for me many years ago when I went to Shanghai.  Armed with a map from 1939 and a modern one, I was able to locate all the places my parents lived, worked and hung out during WW2.

Good luck,

Vicky Ferraresi 
Belmont, CA