From Chapter 14 of A Pattern Language:
People need an identifiable spatial unit to belong to. Today’s pattern of development destroys neighborhoods. … Help people to define the neighborhoods they live in, not more than 300 yards across, with no more than 400 or 500 inhabitants. In existing cities, encourage local groups to organize themselves to form such neighborhoods. Give the neighborhoods some degree of autonomy as far as taxes and land controls are concerned. Keep major roads outside these neighborhoods.
Mark the neighborhood, above all, by gateways wherever main paths enter it – Main Gateways (53) – and by modest boundaries of non-residential land between the neighborhoods – Neighborhood Boundary (15). Keep major roads within these boundaries – Parallel Roads (23); give the neighborhood a visible center, perhaps a common or a green – Accessible Green (60)‹or a Small Public Square (61); and arrange houses and workshops within the neighborhood in clusters of about a dozen at a time – House Cluster (37), Work Community (41)….