The city archives are the memory of the state capital. All important documents relating to Mainz's history, from medieval parchment documents to digital data carriers, are stored here and made available to the public.

The archive accepts, evaluates, and catalogs analog and digital files from the city administration that are no longer needed, and collects the estates of important Mainz personalities as well as companies, associations, federations, and political parties. The city archive provides historical education through exhibitions, lectures, guided tours, and publications.