We are digitizing historical city directories (or 'Adressbücher' in German) from the 19th/20th century which contain individual level information about their job, their address and name at a high frequency over time. This dataset would help us in answering some pressing questions for example on urban inequality, sorting of people within the city, or within city migration throughout a crucial time in the urban formation of the city, Apart from some (urban/historical) economic applications, there are many other uses in academia or non-academia i.e. sociology, history, linguistics or people interested in biographies or genealogy. There had been a lot of work of non-researchers, particularly people interested in genealogy, typing these city directories by hand into digital form. This polydata group aims to bring us all together under the common, massive goal of digitizating city directories as an invaluable source of information for research. This polydata groups aims to exchange experiences about the OCR (optical character recognition) as well as geocoding. It furthermore aims to be a centralized place to exchange scans of city directories, either by providing links to already scanned books published by various libraries, or by uploading a personally scanned book through this platform for others to work on.