Demographics of Cologne and on 1 April 1888 ended in a first major incorporation. The territorial expansion, beginning in the late 19th century, were significant marks for the city's population growth. Major communal reorganizations took place in 1910, 1914, 1922 and 1975. Demographics of Cologne Cologne () is Germany's fourth-largest city and the largest city in the Rhineland. As of 31 December 2011, there were officially 1,017,155 residents. The city is center of the Cologne/Bonn Region with around 3 million inhabitants (including the neighboring cities of Bonn, Hürth, Leverkusen, and Bergisch Gladbach). The walls of Colonia Agrippina covered an area of 96.8 hectares,
NS Documentation Centre of the City of Cologne the best pre-served prisons from the Nazi era, representing an historical asset of national and European importance. Since June, 1997, the permanent exhibition in the EL-DE building has depicted political, social and community life in "Cologne During the Nazi Era." That includes the seizure of power and the power apparatus, propaganda and the "national community," everyday life, youth culture, religion, racism, the genocide of Cologne's Jews and its Sinti and Roma, and opposition, resistance, war and society during war. In addition, temporary exhibitions depict local and national aspects of the Nazi regime. The center also mounts more than 130 events