The estimate comes from auditors working for the state of North Rhine-Westphalia and exceeds the €950 million cost of the controversial four-kilometer subway tunnel through Cologne that is thought to have been the cause of the building's collapse. The March 3 accident killed two men who lived in a neighboring building.
Experts believe the collapse was caused by problems at the underground construction site near the archive. Media reports revealed that construction managers and city officials saw measurements that clearly showed the archive was sinking weeks before the building collapsed into the nearby underground metro construction site.
The city has since opened an investigation into what caused the accident and has raided the offices of construction companies involved in the subway line's construction.
Archivists sifting through the rubble announced last week that they had recovered the Nobel Prize certificate of famed writer Heinrich Böll, who was a native of Cologne.
“It was found in an archive box and is in good condition,” Bettina Schmidt-Czaia, the archive's director, told the daily Kölnischen Rundschau on Thursday. Most of Böll's collected documents had only been placed in the archive just three weeks before the building's collapse.