The present Study addresses recent achievements in better representation Of the urban area structure in meteorology and dispersion parameterisations. The setup and Main Outcome of several recent dispersion experiments in Urban areas and their use in model validation are discussed. The maximum concentrations generally are predicted within a factor of two by the best models. If the plume is released down in a closely-packed set of obstacles, it is necessary to account for initial spread. If the plume is released above the obstacles, there is less of an initial spread. For roof level releases (the BUBBLE Tracer Experiment) the horizontal spread of the plume corresponds to a Lagrangian time scale bigger than the value for ground Sources. Turbulence measurements LIP to 3-5 times the building height Lire needed for direct use in dispersion Calculations.