Metadata of the "Alter Realkatalog" (ARK) of Berlin State Library (SBB) Version 2 - August 2025

This dataset was created with the intent to provide a single larger set of metadata from Berlin State Library for research purposes and the development of AI applications. The dataset comprises descriptive metadata of 2.639.554 titles derived from the union catalogue K10plus, a database with about 200 million records from libraries across 11 German states. Selected are all records that include system entries ("Systemstellen") from the historical classification of the "Alter Realkatalog" (ARK), a subject catalogue of the Staatsbibliothek zu Berlin – Berlin State Library. They refer to publications from 1501 to 1955 and reproductions thereof. The title data contain subject headings and BK classmarks that have been transmitted onto them from the "Historische Systematik", the online representation of the ARK classification.