The Warsaw Ghetto, located in the heart of the city, was the largest ghetto in Nazi occupied Europe, with over 400,000 Jews crammed into an area of 1.3 square miles (3.4 km2).[7] The Łódź Ghetto was the second largest, holding about 160,000 people.[8] According to the United States Holocaust Memorial Museum archives, there were at least 1,000 such ghettos in German-occupied and annexed Poland and the Soviet Union alone.[4]