||We are facing a constant growth in 3D GIS, and its interaction with CAD, VR and CG, influence each other more than ever. In this context, 3D urban models can interactively assist in any step of a decision making process. Urban planners can benefit from 3D urban models in a way never thought before. PC technology , free 3D interactive viewers and VRML offer low cost implementations. Data coming from cadastral updates in Argentina are an invaluable source of digital data and building height attributes are included on that. In that way, tabular or attribute data can be linked to 3D graphic data. Geographic Information Systems can add to these 3D urban models all the benefits of attribute data plus its spatial analysis capabilities. Queries of any kind, and links to hypertext, planning documents can enhance the information provided by this "virtual world". Finally, regarding communication aspects, Interactive design and decision making can be reached in a much easier way as 3D is better than 2D. If we consider that 3D urban models can easily be browsed in VRML we have then the enormous potential of collaborative design through internet and intranet.