Look, Germans created ghettoes for Jews in the worst, dilapidated districts.
But before the war, although there were some districts in cities with a Jewish majority, Jews were intermingled with the Polish population. Many people were just Jewish-Polish, like in the US now.
Then came the war, and only 5% of Polish Jews were left. Then came the year 1968, when the party quelled unrest by claiming that the protest leaders were Jews. After expulsions, only 5000 Jews remained in Poland.
Many synagogues were turned into ordinary buildings after the war, for lack of worshippers.
If you go to Warsaw nowadays and see the "Jewish ghetto", it's nothing concrete. The buildings were destroyed in the fighting in 1943.
The ghetto was very close to the old town, so in the city centre.
150 Jews are left in Cracow, a result of the war. But you can see several synagogues in the Kazimierz district.
(at the bottom)