This article attempts to assess how a modern urban area consumes energy either directly or indirectly. One of the most important outcomes of this study is a complete picture of an urban energy system, i.e., the entire source-service fuel cycle involving the sources, transportation modes, distribution channels, and consumption pattern of all the energy carriers for a period of 10 years (1980-90) for Bangalore, a city in southern India. The study also led to a detailed end-use analysis of energy carriers, and a source-service matrix is prepared for Bangalore. The impact of energy consumption on forests, environment, transportation, and the economy as a whole is discussed here.