Effective crime prevention planning includes physical planning, or environmental design. Land use and abuse (i.e., the different ways in which land can be used to serve legitimate and illegitimate interests is part of physical planning. This paper examines the concept of optimal land use, which has a circumstantial and temporal framework that even modern feasibility studies, evlauations, and cost-benefit analyses can never wholly resolve (e.g., yesterday's mistake or even fraud can result in today's public benefit, whereas yesterday's apparent optimal land-use decision can result in today's economic disaster). Social and architectural determinism should be avoided in environmental design for crime prevention, which must try to anticipate future crime patterns and to improve the quality of life be learning from past mistakes. The concept of defensible space, developed in 1968 by a group studying ghetto life at Washington university in St. Louis (i.e., a space which is defensible against criminals, vandals, and intruders) is explored in connection with urban planning in New York, Philadelphia, Boston, Cleveland, Newark, and Minneapolis. The presence of the police as the best crime deterrent was also incorporated into the defensible-space planning concept through environmental design aimed at facilitating police surveillance and intervention. Other crime prevention features of environmental design should include the use of parks for activities that attract people and reduce the number of hours that recreational areas are abandoned to exploitation by criminals. Thirteen endnotes with references are appended.