- The private papers of the Nobel prize-winning novelist Heinrich Böll, one of Germany's most famous postwar writers
- Manuscripts of essays and articles written by Karl Marx when he was editor of the Rheinische Zeitung in Cologne in the 19th century
- Letters written by the philosopher Hegel
- Lyrics and notes written by the composer Jacques Offenbach
- Edicts issued by Napoleon and King Louis XIVth
- The personal papers of Konrad Adenauer, West Germany's first Chancellor and former mayor of Cologne
- Minutes of all town council meetings held since 1376, a remarkable resource for legal historians
The Times reports that the "earliest document stored in the building dated back to 922, and there were hundreds of thousands of documents spread over six floors, some of them written on thin parchment. A total of 780 complete private collections and half a million photographs were being stored." The collapse was nearly instantaneous: "Workers on the rooftop heard a cracking noise and immediately alerted the 26 people using the archives at the time. Less than three minutes later later, the building was flat."