The design of new investments with underground floors in the downtown urban fabric calls for determining its impact on existing, often historic, neighboring facilities. The article presents the results of own research on 3D spatial arrangement numerical modeling of this type of investment. The scope of the research includes the analysis of neighboring buildings (including historic buildings), construction of the 3D numerical model, and calibration of the subsoil model taking into account the actual results of geodetic measurements. Own research as well as the completed housing development complex in Poland, downtown Warsaw, including data from project design and implementation documentation serve as the basis for research and analysis. As a result of said research and analysis, it was found that 3D computational models allow mapping of actual impacts within the designed new buildings and neighboring buildings, and as consequence - after appropriate calibration - a good reflection of soil displacements in the area of the planned investment. The knowledge of the anticipated values of soil displacements related to erecting new buildings is necessary at the design and implementation stages to ensure safety in all phases of works of existing buildings.