Demographics of Cologne 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, but the population density within the walls remains uncertain. Since the construction of the Medieval wall in 1180, the area of the old imperial city of Cologne has not changed for more than 600 years and was only extended
Historical Archive of the City of Cologne the 1897 building has been used as a private library by Gerling, a large insurance company. In 1971, a six-story archive building by architect Fritz Haferkamp was built on Severinstraße in the southern part of Cologne's city center. An underlying principle of the design was to protect archival records from fluctuations in weather and climate while creating a balanced room climate. In a move away from the contemporary popularity of electromechanical air conditioning, Haferkamp preferred a structural-physical, self-regulating solution that needed only little additional climate technology. As the "Cologne Model", the building became a model for many later archive buildings