For the first time in history, the majority of the world's population is residing in its cities. Expended resources and climatic concerns are prompting a shift from traditional patterns of growth, predicated on the burning of fossil fuels, in favor of innovative, sustainable strategies. This thesis demonstrates the implications of this trend in the DC | Baltimore area, in the proposal of a closed-loop symbiotic-network city that will be linked both by alternative means of transit but more importantly by a lifeblood of inter-relational sustainable systems. The project's design develops at three scales; [xL] regional - through the establishment of an infrastructural and transit network between developable brownfield and greenfield sites in and around Baltimore and Washington DC, [L] district - in the development of one site into a mixed-use neighborhood, and [s] building - by the design of a civic edifice that serves as a pronounced model for the whole.