Friedman expanded on the principles for Mobile Architecture to the idea to create an elevated city space where people could live and work in housing of their own design (see also self-planning), the Spatial City. With this idea he also hoped to introduce a methodical approach to enable the growth of cities while restraining the use of land. Projecting the Spatial City on real life locations Friedman meant to explain the advantages of the idea and furthermore that it was not necessary to demolish older city parts to create new housing. Compacting the city, as building above the existing city, could also diminish expanding the city outwards.
Friedman designed methods of choice for future inhabitants to enable them to create and position the living space they wanted. These were published in the so called Manuals and integrated in a computer program called The Flatwriter in 1967. Friedman combined many of his principles: the flexibility of housing to enhance the freedom of choice for the individual, the flexible multilayered use of city space, and the grip of city dwellers to give meaning to their environment. He opened a wide field of discussion on the fundamental right to self expression of individuals, on the inclination to build more and more, and on ways to be self sufficient in a modern society. These topics implicated subjects as the role of the state, the role of capitalism in urbanism, the use for architects and the matter of respect for the natural environment.
In the earlier years he made studies on the technical feasibility of the project, later his ideas and projects served mainly to help people to think outside the box and enhance awareness to the idea that an unconventional approach may well yield good solutions for the ongoing problems of our modern cities. From 1998 on, his ideas regained worldwide interest and Friedman was once again invited to make exhibits and give lectures.
Principles of the Spatial City
The Spatial City is a multilayered structural skeleton (grid) on stilts that can be flexibly adjusted when desired. The structure is supported by columns (stilts) that are situated at an interval of 40-60 meters and which houses the accesses and facility networks. The base of the grid is 6×6 meter module that can accommodate all kinds of functions. In the skeleton all sorts of units for housing and work can be fitted in. In between there is free space, arranged so, that natural light can reach the ground underneath.
Inhabitants will be free to decide how their dwelling should look. To get to a balanced combination that would serve to avoid conflicts he invented a model for communication. He designed a program of methods of choice for future inhabitants to enable them to create and position the living space they wanted, a so called Flatwriter. This program should enable the inhabitant to succeed in self-planning and make it possible for constructors to directly realize the dwellings without the use of an architect. A model of Spatial City can be fitted over less used areas in a city, for instance railroad complexes. The goal is to be able to expand the city within its boundaries and without demolishing the existing buildings.
Models of Spatial City
Friedman used photomontages of actual city sites to explain the principle. Especially the montages of the centre of Paris published in 1959 gained wide attention and accelerated his principles to other themes of discussion. From 1998 Friedman's ideas regained a lot of interest.