Today, both resource efficiency in general and the efficient use of natural resources specifically in the building sector are major political issues. Recent studies on resource efficiency have found the "anthropogenic stock" of the building sector to outweigh natural resource stocks. To make the anthropogenic stock accessible, material quantities with their individual composition need to be estimated and extrapolated to regional level. A geographical information system (GIS) is used as tool to handle the building specific data and combine them on regional level to calculate the anthropogenic stock. The resulting resource cadaster reflects the material quantities, divided into sixteen material fractions, of a specific residential district in the Rhine-Ruhr metropolitan area-a typical urban area in Germany. The case study area was weighted in total between 103.5 kt and 93 kt, depending on the dataset. This paper offers a step-by-step description of this approach, whereby a consistent dataset was created throughout the process of data collection and validation. In order to demonstrate the broader application of the resource cadaster, the results were extrapolated to the residential building sector of the entire federal state of North Rhine-Westphalia. In highly concentrated areas, like the Rhine-Ruhr Metropolitan area, both area-wide classification of material quantities and their regional localization are necessary to make the anthropogenic stock accessible. Information about toxic substances, however, also needs to be included in the process of data collection. This method of mapping could thus provide the foundation for future (re)uses of this stock. This study offers some concrete steps in the direction of achieving a circular economy.