Problems associated with increased noise exposure especially due to road traffic in the urban context are well known. Theoretical knowledge about sound propagation and acoustical simulation software are already available, however, the acoustic planning of outdoor urban areas and the potential of simulation still does not receive sufficient attention. In this context, the present contribution focuses on urban canyons via comparison of measured and simulated sound levels. Toward this end, a commercially available room acoustic simulation tool was deployed to model two inner-city areas in the city of Vienna, Austria. Thereby, geometric data was obtained from an existing repository and subsequently adjusted to fit the input requirements of the selected application. Furthermore, multiple sources of information were consulted to specify material properties such as the absorption coefficients of the relevant surfaces. Likewise, assumptions pertaining to the sound power of pertinent sources were made based on applicable standards and in-situ observations. Thereby, the agreement between simulations and measurements can be qualified as satisfactory. The contribution includes also a sensitivity analysis that takes into account variations in model assumptions, including factors such as surface characteristics, traffic flow, receiver positions, and the simulation tool's settings. Thus, the calibration potential of acoustical simulation tools in urban planning applications can be explored.