The 'Object Based Image Analysis' approach (further, OBIA) becomes increasingly popular and is being used for classifying VHR remote sensing images. The use of this innovative approach for urban mapping is highly effective as it makes possible to include information about features, shapes and other characteristics of urban space and to interpret them to study land cover types. Using very high resolution (VHR) image for mapping enables to identify land cover and land use types within urban environment. Hence, the OBIA approach for processing remote sensing data creates effective tools for urban studies. Furthermore, the application of the priori knowledge is necessary for the case studies where additional knowledge can implement detailed information into the existing databases, e.g. information on land cover and land use types, roads, buildings, vegetation units (parks), etc. Particularly useful becomes a priori knowledge for incomplete or outdated databases (containing e.g. missing areas, or those inside of closed blocks, etc). Additional knowledge about the city structures and urban features should be included while interpreting image. The case study of the current research is focused on the eastern part of Brussels, Belgium.