The former library of the observatory of the city of Düsseldorf is essentially the private library of its founder, the Düsseldorf mathematician and astronomer Johann Friedrich Benzenberg (1777-1846). The collection has been part of the holdings of the former City and State Library of Düsseldorf as a deposit since 1907 and as property since 1923.

As a universal library of scholars, the Benzenberg Collection contains general reference works as well as fiction, theology, philosophy, state and legal history, and an extensive pamphlet collection on constitutional and economic issues. The focus is on scientific literature, especially astronomical, physical and geodetic literature.