The paper discusses about architectural and urban design tools, and reports a prototype of parametric application that allows the designer to handle the architectural shape by using urban regulations. It is a Decision Support System (DSS), useful at the early stage of city planning as well as at the early stage of architectural design. The System integrates two different research topics: modelling in geo-referenced environment and modelling through constraints. Compared to the related works (Building Modelling on geo-referenced environment), our application is the first Generative System based on the urban regulation. Three case studies are presented to test the System
