This paper challenges the prevalent 'green building' design approach that treats nature as a resource rather than a living eco-system(s), and aims only to minimise the net negative impacts on the environment. It argues that buildings and cities could increase the ecological base as well as improve the economic and social health of surrounding regions. Genuine Sustainability would require the eco-retrofitting of existing development to provide the infrastructure and space to improve ecosystem health and increase natural capital. The good news is that this can be done without sacrificing space for human functions, amenity and life quality. However, it would require a very different kind of environmental management, planning and design.