Massive, exposed concrete, honest, and raw are words you might use to describe Brutalist Architecture. Favored by government institutions during between 1960s-1980s for low cost constructions, this unique style was a response to the lightness and optimism of 1940s architecture as well as a descendant of Modernist Architecture of the early 20th century.
Architects such as Le Corbusier championed the style. Brutalist buildings employ the use of raw concrete for its raw and unpretentious honesty, a stark contrast to the highly ornate buildings of the competing Beaux-Arts style. Brutalist surfaces often reveal the basic nature of their construction and repeated modular elements form masses representing specific functional zones.
In short, Brutalist architecture unabashedly shows you how it was built, with what it was built and why it was built. It is blunt with its message and function, we should all be a little more Brutalist.