The branch of architecture dealing with the design and organization of urban space and activities WordNet 3.0 & Open English WordNet

Urban planning, also known as town planning, city planning, regional planning, or rural planning, is a technical and political process that is focused on the development and design of land use and the built environment, including air, water, and the infrastructure passing into and out of urban areas, such as transportation, communications, and distribution networks and their accessibility. Wikipedia

The activity of designing, organizing or preparing for the future lay-out and condition of a city or town. OmegaWiki