As the move towards sustainable urbanism grows, understanding how the city has previously been envisioned and designed will be useful to moving forward. This work examines the legacy of urban design theories, what these theories have implied about what the city should be, and their sustainability consequences. Noticing three prominent urban design visions of the city, the technological city (as proposed in 1922 by Le Corbusier's Ville contemporaine and later in 1933 by his Ville Radieuse (The Radiant City), and in 1935 by Frank Lloyd Wright's' Broadacre City), the social city (as explored in 1961 by Jane Jacobs and in 1976 by Edward Relph of the University of Chicago), and the ecological city (as expounded upon in 1924 by both Lewis Mumford and in 1969 by Ian McHarg), I have newly applied the social-ecological-technical systems framework (SETS) to help classify and analyze these urban design theories and how they have mixed to create hybrid perspectives in more recent urban design theory. Lastly, I have proposed an urban design theory that envisions the sustainable city as an ongoing process. Hopefully, this vision that will hopefully be useful to the future of sustainable development in cities, as will a more organized understanding of urban design theories and their sustainability outcomes.