ABSTRACT
To understand their original analogy to the biological process of metabolism—as the most essential one among basic life properties for the Metabolist urban theory—Kisho Kurokawa's theoretical writings and some of his Megastructure projects are overviewed by the author. In the fourth part of the Metabolism manifesto under the title "Urban Design for New Tokyo", Kurokawa disclosed his idea of 'metabolic cycles'. His idea was based on that the different functions of a city have different life cycles, just as different parts of living organisms have different cycles of renewal. He thus proposed that functions with similar life cycles in the city should also be grouped in order to create a new order in cities, and groups should be connected to each other in a flexible manner: There exists a changing cycle differing according to each section of the city. There exists a difference in the durability and scale in the basic urban structure, urban connectors, living units and architectural equipment.
