The ghettos.

Once Hitler had everyone thinking the way he did, he began the persecution of Jews, Gypsies, Roman Catholics, and others. Particularly, the Jews. They didn't start in the famous death camps however. They started in Jewish ghettos. The ghettos were only the beginning of the Final Solution. They were a place where the Germans knew the Jews would be and easy to move about. These ghettos were too small for the amount of people living there, and not sanitary enough to keep its occupants healthy. Many people died before it was decided that they would be sent to the death camps.