History of Cologne was considered a substitute for the German University of Strasbourg, which became part of France along with the rest of Alsace. Cologne prospered during the Weimar Republic and progress was made especially in governance, city planning and social affairs. Social housing projects were considered exemplary and were copied by other German cities. As Cologne competed to host the Olympics, a modern sports stadium was erected at Müngersdorf. Beginning of the 1920s civil aviation was permitted once more, and Cologne Butzweilerhof Airport soon became a hub for national and international air traffic, second in Germany only to Berlin Tempelhof Airport. At
Historical Archive of the City of Cologne of photographs on the history of art, architecture, culture and photography in Cologne and the Rhineland. The plan was to build the “safest and state-of-the-art city archive in Europe“ by 2017. After the decision of the city council, a detailed concept was worked out and approved. In 2013, in the context of the city's financial crisis, local political debate began to move towards re-considering this decision, and even to imposing a planning moratorium. Protests by local support groups as well as national archive organizations followed. In 2017, the total damage from the collapse was estimated at 1.2 billion euros. Before