How many ghettos where there in Germany during the Nazis?

The Nazi ghettos for Jews were mainly in Poland, Lithuania, Belarus and other parts of Eastern Europe. In 1939-40 German Jews in most larger cities were forced to move into 'Jewish' appartment blocks, which were marked as such with a large J above all entrances. In most of Nazi Germany itself Jews were not put into ghettos in the sense of walled in areas. The Nazis know that that would lead to too many questions from ordinary Germans.