An inquiry into the loss of urbanity in the contemporary city initiated a historical study of public space. The public space of today's mall is introverted and isolated from its environment--the disintegrated, decaying city. The political implications of this transformation are the tendency towards privatization of public space and increasing segregation of society. Public space and public services are more and more taken over by profit-oriented private businesses and no longer available to everybody, e.g. the 'central business district' demonstrates the replacement of the public realm by the corporate realm. The Houston tunnel system exemplifies this tendency: it is owned by private corporations, accessible to the public only from their buildings. The Design Thesis attempts to return this part of the urban infrastructure to the public realm. Entrances from the street are intended to make the pedestrian tunnels more easily accessible to the individual.