Brutalism is an architectural style defined by its honest usage of raw concrete and intense massing. A successor of the Modernist movement, Brutalism is likewise considered to be a reaction against the perceived excesses of decoration and nostalgia of earlier architecture. It was popular from the 1950s until the early 1980s. Brutalism is most infamous for its socialist ideals and usage by Communist regimes, like the USSR.
The etymology of Brutalism does not come from the term "brutal;" instead, it derives from the word "brut," which is French for "raw." (e.g. "beton brut" -- "raw concrete," "art brut" -- "raw art.") Beton brut, a type of unfinished concrete that contains the texture of its formwork, is a very common building material used in Brutalist architecture.
The first project described as "Brutalist" was the Villa Goth in Sweden, designed in 1950. Architect Hans Asplund identified the house as such due to its materiality (brick walls, concrete with visible patterning from the wooden formwork, and I-beam lintels). However, what is considered to be the catalyst of the style is Le Corbusier's Cite Radieuse, built in Marseille between 1947 and 1952.
The idea of Brutalist architecture began to grow rapidly with young architects in Britain during the early 1950s, as the country recovered from the destruction of World War II. Designs that were both functionally and materially honest were desirable, and limited materials prevented the excesses of orthodox Modernism.
The principles of Brutalism resemble those of the larger Modernist movement, mainly a reaction against the nostalgia and heavy decoration of earlier architecture. The most apparent is the honest usage of materials and expression of structure. This generally manifests itself in the intense massing, raw concrete, and perceived "coldness" of the architecture. In terms of the actual organization of program, many Brutalist buildings are modular and functionalist. A common feature was "streets in the sky," a circulation method that provided access to apartments while enabling views of a building's surroundings. Brutalism is also rooted in the Socialist movement, as it was meant to be anti-bourgeoisie and create utopia through architecture. As a result, many examples of Brutalist architecture are public housing or government buildings.
Brutalism declined in popularity due to changing tastes and the economic/political environment. However, many works still serve as precedents today, due to the style's ideals of honesty, purity, and strength.