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
Historical Archive of the City of Cologne libraries that did not suffer major losses during the French occupation in the early years of the 19th century. After the secularization of abbeys and colleges of canons in Cologne in the early years of the 19th century, the French government ordered their archives to be stored in the state archives in Düsseldorf. It was not until 1949 that a mayor of Cologne succeeded in recovering 19,000 charters and many other records for the Cologne municipal archives. In 1818, the city of Cologne was bequeathed Ferdinand Franz Wallraf's major collection of art, books and manuscripts. After Wallraf's death in 1824,