The current type of subdivision that is protruding into the rural areas in what has been commonly referred in modern societies as sprawl is unsustainable from both an environmental and social perspective.
While Paolo Soleri has developed Arcology as a very compact alternative to low density suburban American style development and has sought to promote Arcosanti as the world's first prototype Arcology, the actual reality at Arcosanti is so early in its stages of evolution that it does not at the present time fit the model or criteria of a Arcology Megastructure.
Reyner Banham, in his book "Megastructure...Urban Futures of the Recent Past" (1976), loosely defines a megastructure as a multi-functional building, irrespective of absolute size.
* Mesa Verde Pueblo
* aircraft carriers
* the Ponte Vecchio (in Firenze)
* deep sea oil platforms
* Cumbernauld Town Centre (Scotland), etc.