The Change of the Study of the conditions and directions of spatial development for the city of Ostrołęka covers the area of 2,860 ha. The aim of the document is to update the city resources – public spaces, residential and service areas – as well as define directions for the city’s spatial structure, based on the conditions resulting from the existing development and development opportunities in connection to the socio-economic situation. In the city center, areas for residential and service development were marked out, among which local service centers are located. The Narew River divides the city into two functional zones: one, which together with a strip of meadows and wetlands, forms an ecological corridor that plays an important role in the European Ecological Network Natura 2000 system, and the second which is an area of urbanization. The city, which has an industrial character, developed mainly on the left bank of the Narew River, where the certain phases of its development are clearly visible, ranging from the medieval division of plots in the city center to the radial road system connecting the city center with residential and service or industrial areas and a railway line.