According to Doxiadis, the greatest problem facing cities worldwide was the problem of managing growth. Far too often, he argued, city planners made inadequate provisions for urban growth and as a result cities would grow like cancers, the inner core eating into surrounding neighborhoods and the outer edges gobbling up the natural landscape. He proposed several solutions for rapidly growing cities, one of which was for city planners to leave room for expansion of the city core along a predetermined axis so that most urban expansion would be channeled in a single direction. This innovation would, he suggested, release the population pressure on the urban core while leading to a more orderly development of the outlying area. In cases where multiple metropolitan areas were growing together as a megalopolis Doxiadis suggested that new self-contained urban centers be created within the urban sprawl with improved communication and transportation links between them.
In later books, Doxiadis became increasingly interested in the philosophical underpinnings of urban development. In Anthropopolis: City for Human Development (1974) and Action for Human Settlements (1976), he suggested that planners must concentrate above all on making humane cities. Since the existence of big cities was inevitable, as was the proliferation of space-expanding technologies like automobiles and skyscrapers, Doxiadis concluded that planners must find ways to restore human scale to large cities. Some of his proposals included
- Limiting all buildings to three levels or less, with permission to build higher bestowed by national authorities.
- Separating automobile and pedestrian traffic completely, with automobiles consigned to underground conduits if possible.
- Constructing cities as a "beehive" of cells each no bigger than 2 by 2 kilometers, the maximum comfortable distance for pedestrians.
Ultimately, Doxiadis was optimistic that with proper planning the cities of the world would eventually mature into a stable and pleasant form he called the ecumenopolis. Doxiadis worked for more than a decade to establish an interdisciplinary community of scholars who would complete research on cities and the best ways to manage them. Ekistics, the journal Doxiadis founded, continues to publish articles on a wide range of urban topics. Although his work is rarely explicitly referenced in urban planning literature, many of his ideas have been integrated into mainstream academic and popular thought. The New Urbanism movement of the 1980s and 1990s, which suggested that small pedestrian friendly villages should replace typical suburban developments, echoed many of Doxiadis' suggestions (Calthorpe 1993, Leccese and McCormick 2000)
