Where there is nothing, everything is possible.Walden, in allusion to the novel written by Skinner, describes an experimental community located in areas of pressure and hyperdensity with the aim of improving current life conditions of the population.Walden studies cities that have become extremely large, with overpopulated suburbs and bad living conditions, such the favela of Parasaipolis in Sao Paolo, Zharavi in Mumbai or the previous existing Walled City in Hong Kong. Walden proposes a new vertical cluster organization to improve this dense organization that has problems with water, nutrition, or cultural knowledge.The choice is clear: either we do nothing and allow a miserable present for these people or we use our knowledge about human behavior to create a social environment in which they shall live productive and creative, not only survivors. Walden is a selforganizated city, based on the blooming of clusters that mixes programs. Population of around 1000 people creates a community which is self sufficient, with a correct balance between public and private space, with new infrastructures and the possibility of interaction with other clusters. The community itself builds the cluster, in a process of culture engineering and cooperation.