Every major city needs space for the youth to gain access to free information concerning natural building, growing one's own food, rainwater catchment and small scale energy systems, as well as space for youth to practice and experiment with building shelter, growing food, capturing rainwater and installing small scale energy systems. These are the things that compose sustainable living. To live a sustainable lifestyle, all one has to do is find access to land, build a house, plant trees, grow a garden, start a plant nursery, keep bees, capture rainwater and establish ones own energy supply (given one is even needed). Once these skills are understood and mastered, then one can get on with their lives and either earn side cash through various artisan or nature crafting enterprises (or through any number of other side vocations).
Nothing here is that complicated. Study permaculture (free). Intern (free). Find land (can be free). Live. End of story.