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A megastructure is a very large manmade object, though the limits of precisely how large this is vary considerably. Some apply the term to any especially large or tall building.〔("about the Megastructure" )〕〔 ("The Modern Urban Landscape" ) by E. C. Relph 〕 Some sources define a megastructure as an enormous self-supporting artificial construct. Other criteria such as rigidity or contiguousness are sometimes also applied, so large clusters of associated smaller structures may or may not qualify. The products of megascale engineering or astroengineering are megastructures. Most megastructure designs could not be constructed with today's level of industrial technology. This makes their design examples of speculative (or exploratory) engineering. Those that could be constructed easily qualify as megaprojects. Megastructures are also an architectural concept popularized in the 1960s where a city could be encased in a single building, or a relatively small number of buildings interconnected. Such arcology concepts are popular in science fiction. Megastructures often play a part in the plot or setting of science fiction movies and books, such as ''Rendezvous with Rama'' by Arthur C. Clarke. In 1968, Ralph Wilcoxon defined a megastructure as any structural framework into which rooms, houses, or other small buildings can later be installed, uninstalled, and replaced; and which is capable of "unlimited" extension. Many architects have designed such megastructures. Some of the more notable such architects and architectural groups include the Metabolist Movement, Archigram, Cedric Price, Frei Otto, Constant Nieuwenhuys, Yona Friedman, and Buckminster Fuller.〔("Megastructure reloaded: megastructure" )〕 This type of framework allows the structure to adapt to the individual wishes of its residents, even as those wishes change with time.〔 Anthony Paine ("Mega structure" ). Architectural Review, The. . FindArticles.com. 15 September 2008. http://findarticles.com/p/articles/mi_m3575/is_n1201_v201/ai_19498628 〕 Other sources define a megastructure as "any development in which residential densities are able to support services and facilities essential for the development to become a self-contained community".〔 ("Future Forms and Design for Sustainable Cities" ) by Michael Jenks, Nicola Dempsey 2005 〕 ==Existing== There are structures that may be considered megastructures, such as *The Great Wall of China is a human-built megastructure, a few meters wide and in length, about .〔Damian Zimmerman, (ICE Case Studies: The Great Wall of China ), December 1997〕 *The Rice Terraces of the Philippine Cordilleras, a sprawling agricultural landscape carved in the mountains by free tribesmen of Ifugao some 6,000 to 2,000 years ago.〔(nscb.gov.ph, FACTS & FIGURES, Ifugao province )〕 *Skyscrapers represent our current state-of-the-art in large structure engineering. (See the List of tallest buildings in the world and list of largest buildings in the world.) *The Large Hadron Collider consists of, among other structures, a ring 27 kilometers in circumference. *The Expressways of China are the longest expressway system in the world. Networks of roads or railways, and collections of buildings (cities and associated suburbs), are usually not considered megastructures, despite frequently qualifying based on size. However, an ecumenopolis might qualify. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「megastructure」の詳細全文を読む スポンサード リンク
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