Brown is the new green

B rownfield sites are a common eyesore on the edges of many cities; the abandoned, decaying hulks of industrial or commercial structures sit rusting and forgotten while they leach harmful chemicals such as asbestos, solvents or heavy metals into the soil. Some brownfields lie virtually untouched for years because it is often cheaper to expand cities into virgin territory than to demolish large structures or engage in the costly clean-up of contaminants. But in many urban areas in developed nations, especially in Europe, land has become increasingly scarce around cities and brownfields have become more attractive economically for new development.