As part of our national and worldwide efforts to minimize the impact of our growing human population on planetary resources, and to minimize our production of greenhouse gasses, we need to capitalize on the energy and resource efficiencies of relatively densely inhabited already built-up areas. These kinds of places are more walkable, have greater public amenities, more variety, are better served by public transportation, and have more efficient infrastructure than more diffusely populated areas. Every new retail, office, small scale manufacturing, research, and particularly residential building that is constructed in already built-up areas, such as the City of Cambridge, is is a building that is not built in outlying suburbs, with their dependency on automotive transportation and more extravagant per capita use of material resources. Density can be our friend. When coupled with design strategies that strengthen a sense of place by promoting the spatial definition and quality of public open space - the city's streets, parks, and squares - density improves the quality of life for residents and other users of the city. Few people would choose to live in Cheyenne Wyoming or the suburbs of El Paso if they could instead live in Paris or Rome or Venice (or even the Italian hilltown I know best, Aidone). Cambridge can and should serve as an example of high quality urban design that is energy and resource efficient and improves residents' quality of life. The City's Master Plan should be directed toward this goal. Three initial steps that come to mind: Map all the underutilized sites in Cambridge: parking lots and one floor retail buildings on our major streets, and view them as siting opportunities for substantial and well designed buildings. Review existing zoning regulations: heights, setbacks, build-to-lines, etc., and adjust them if necessary so as to promote the construction of buildings that contribute to a dense environment of high spatial and aesthetic quality. Preserve Cambridge's best buildings - the ones that not only have high quality facades, but also contribute to the quality of public space by their massing and siting. (eg: the Odd Fellow's Hall in Central Square and the (ex) Globe Corner Books Building on Mt Auburn Street), and encourage designers of new buildings to emulate their positive characteristics.