The cities of the world are great engineering feats. From the earliest dwellings of man constructed out of the raw materials of the environment, man has used his ingenuity to work engineering wonders that improve the circumstances of human life. By engineering technological skills, human beings have altered the environment to suit varied activities. Bioengineering refers to the medical application of engineering to severe human problems of prosthesis. The same concept can be put to use in the larger human environment. Ecologists have an array of terms to describe community and environmental conditions, i.e., the ecosystem. Through the use of engineering skills, cities can be made better than they are, but first, knowledge about ecological principles as they relate to cities must be enlarged. (Author/AM)