Geographic Information Systems (GIS) present one of the most important 3D modeling techniques of cities, which has become a very important and necessary for representing of contemporary cities, and doing different analyses, with the aim of finding solutions to the problems raised through a virtual model of reality. In addition, 3D GIS play an important role in urban planning. Despite the presence of a large number of programs capable of dealing with 3D objects, many of these applications require high technologies and advanced tools for the representation and analysis of 3D objects. The objects of 3D models represented in GIS can be associated with a set of queryable attributes, and this is not available in other 3D modeling software. This Research aims to highlight the importance of procedural 3D modeling of cities in GIS environment using ESRI CityEngine. A set of CGA (computer generated architecture) rules - programmed by procedural modeling language in CityEngine- will be presented to generate realistic 3D models that can represent all elements of cities and its infrastructure. Then, all the objects will be exported to a Web Scene viewer, which allows the creation a comprehensive platform to present a system to support decision-making, and facilitate project management related to the management of cities. The research methods will be applied to Tartous governorate through designing and modeling of proposed residential area. This study will include CGA rules applied to create a 3D model of proposed area, it will show the importance of GIS in modeling and representation of cities.