Historical Archive of the City of Cologne up at the site of the collapse (a large hole in the ground), where around 95% of all archival items could be held until August 2011, albeit scattered and in many cases badly damaged. Archive repositories all over Germany offered space to store the damaged and only roughly cleaned documents: wet materials were flash-frozen to prevent mold growth. "Itinerant archivists" worked in the receiving archives all over the country and began the task of re-identifying and re-cataloging. A newly installed centre for restoration and digitization on the outskirts of Cologne started working in 2011, with a total cost for restoring
Cologne City Hall gradually changed from a mainly feudal society to free citizens. Documents from the years 1135 and 1152, recorded "a house in which citizen convene", referring to the first established council hall, at the location of today's town hall. The coat of arms of Cologne, first mentioned in 1114, is Europe's oldest municipal coat of arms. By 1180, the citizens of Cologne won a legal battle against Philip I, Archbishop of Cologne, for another extension of Cologne's city walls. With the Battle of Worringen fought in 1288, Cologne became independent from the Electorate and on 9. September 1475 officially gained Imperial