Attribution principle
Every important fact page names its source, last-verified date and confidence. We invent no data; anything unsourced is marked as such.
Sources used (selection)
Official/open data: Berlin data portal (daten.berlin.de), cadastre ALKIS, land value maps (BORIS), development plans (B-Pläne), Statistics Berlin-Brandenburg, Destatis, commercial register.
Geodata: OpenStreetMap (ODbL).
Provider sources: official project pages of developers and municipalities.
Licenses
Open-data licenses (e.g. dl-de/by-2.0, ODbL) are respected and tracked per source in the source registry. Unclear cases hold LEGAL_REVIEW_REQUIRED status until the license is clarified.