In the location's words:

Since its foundation in 1912, the City Archive has been keeping the records and documents that need to be permanently preserved for legal and/or historical reasons.

The City Archives is the institution responsible for the history of the city. We take over, record and preserve the archival documents of the city administration, the council and other bodies. Furthermore, we can take over the records of the city's independent businesses and sitftations as well as associated companies. We can also archive material from Düsseldorf individuals, associations, organizations and companies insofar as they are of significance for Düsseldorf history. For this purpose, we also collect documents that are suitable "to document the history of the city, the cityscape, changes and events as well as the activities of people in the city."

Source: archive.nrw.de