Guben is East-Southeast of Berlin on the Neisse River, straddling the Polish border.
In Poland, the city is called Gubin.
The Polish view is here.
"Since the end of WWII, Guben is a 'divided' city with the former city center located on the Polish side, where the city is called Gubin. ...The Reissners and so many others who lived there before the War ... always mourned that division. ... there is something special about Guben that distinguishes this city from other provincial towns as can clearly be seen from the book 'Poetensteig'. On roughly 160 pages numerous poems by several poets give evidence to that fact, including one by Dorette Reissner de Lobisch, Gaby's mother, in which she tries to cope with the division, although far away in Buenos Aires. I don't know of any other provincial town that was and is loved and revered by so many as is Guben." -- Dorette Schaefer