Megastructure

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.

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. This type of framework allows the structure to adapt to the individual wishes of its residents, even as those wishes change with time.

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".