Necropolis is a concept&sbquo forgotten even in the world of architecture&sbquo which civilization critic Lewis Mumford proposed in 1938 in his book The Culture of Cities&sbquo as the final phase when regarding the development and decline of the city as a phased process. Due to economically centralized wealth and population buildup&sbquo a megalopolis is eventually becomes corrupted&sbquo and deteriorates morally and ethically&sbquo and finally turns into a tyrannopolis. This phase is already in progress in today's Tokyo as seen in a youth culture that seeks momentary pleasure and hedonistic amusement districts. Given this&sbquo the theory that the city will be reduced to ruins eventually due to war or plague has a large element of truth. This state of ruin&sbquo or a dead city&sbquo predicted by Mumford was defined as a necropolis. This is not limited to the phase theory of development and decline of modern cities. It is not implied that the dead city symbolizes wealth due to economical development&sbquo but rather that we should re-member the word as a concept when reevaluating various urban phenomena in the world where wartime regimes&sbquo ethnic conflicts&sbquo famine&sbquo and deprivation occur on a global scale. This concept of urban phase theory should be redefined as the social&sbquo economical&sbquo political and religious background of Mumford's idealistic urban vision not only in the world of architecture but also in the world of design that even includes environmental design&sbquo As to the definition of the city&sbquo international debate should accumulate in the fields of architectural design and environmental design&sbquo and convert the professional idealism of each field into influence on international politics. More-over&sbquo in this century's information society it is important to change the definition of the necropolis itself. It may even be a major means to reconsider the philosophy of professional idealism in the worlds of architecture and design. If we reconsider the concept of necropolis today&sbquo it can be asserted that the city structures of developed nations have been heading towards a manifestation of that dead city ever since the end of the 20th century.