A collaborative virtual environment system is described that is designed to support location-independent shared analysis of spatial data and urban planning proposals. The system seeks to extend the physical workplace of participants into the virtual environment, while preserving traditional textual and verbal communication and cooperation mechanisms. The systems aim is to improve productivity, quality and achieve more transparency in the planning process. The architecture of the Collaborative Urban Planner or CUP system is described and some experimental results that demonstrate urban development control tasks performed within this environment are presented. An application scenario offers a vision of future urban planning practice using CUP. The scenario also diagrammatically demonstrates virtual settings and scenes that could become everyday meeting places for remote planners, architects or engineers assessing proposals and discussing possible alterations to designs.