Brutalist Stair Downtown Atlanta, photo by Isaiah King - Brutalist architecture is a style of architecture that flourished from the 1950s to the mid-1970s, spawned from the modernist architectural movement. Brutalism rapidly became popular with governments & institutions around the world. Examples are typically large buildings, massive in character, fortresslike, with a predominance of exposed concrete construction (wikipedia)
Denys Lasdun, Brutalist architecture - Béton brut - Royal National Theatre, South Bank Lambeth, London. Prince Charles described the building in 1988 as "a clever way of building a nuclear power station in the middle of London without anyone objecting" What does he know.