Brutalist architecture is characterized above all by its exposed, raw concrete — called "béton brut" in French, which gave the style its name. A pioneer of the movement was the famous Swiss-French architect Le Corbusier. Pictured here is a section of his Unité d'Habitation in Marseille, France. Many Brutalist buildings are under threat today; either damaged through neglect or facing demolition.

The National Library of Kosovo was designed by Andrija Mutnjakovic and inaugurated in Pristina in 1982. Its mission is to "collect, preserve and promote the documentary and intellectual heritage of Kosovo." The building itself is intended to represent a style "that combines Byzantine and Islamic architectural forms," according to the architect.

Built in 1971, Miodrag Zivkovic's monument to the Battle of Sutjeska is located in Sutjeska National Park, Bosnia and Herzegovina. It was erected to commemorate some 20,000 partisans who fought against advancing German forces in May and June 1943.

Brutalism experienced its heyday between the 1950s and 1970s. The sometimes monumental concrete colossi were built all over the world, stirring controversy. In India, it was Le Corbusier who stimulated new architectural trends in the 1950s with striking buildings like the Secretariat Building here in Chandigarh or others in Ahmedabad, which inspired many architects.

In recent years, many elaborately illustrated books have been published on the diversity of Brutalist architecture in Eastern Europe. The Hotel Thermal in the spa town of Karlovy Vary in the Czech Republic was designed by the husband and wife team of Vera Machoninova and Vladimir Machonin. A campaign was launched to save the building under the name "Respect Madam."

The gray giants are particularly controversial in the United States and the United Kingdom. King Charles is also a vehement opponent of Brutalism. However, there is no threat to destroy "The Egg" in Alabany, New York. Completed in 1978, the building enjoys great popularity as a Center for Performing Arts.

It was a years-long fight to preserve the Robin Hood Gardens residential complex in East London, built by architects Alison and Peter Smithson. Star architect Zaha Hadid, who died in 2016, was also part of this campaign, but to no avail. In late summer 2017, the bulldozers arrived and demolition work began.

Some Brutalist buildings are now listed as heritage sites. They may not be demolished, but their use can still be problematic. The Preston Bus Station in the UK for example, is far too big for the number of buses that are supposed to arrive and depart here. An architectural firm from New York is now planning a partial conversion which includes a climbing wall, soccer pitch and skate park.

Brutalist buildings are under threat in Germany as well. The project #SOSBrutalism, initiated by the German Architecture Museum (DAM) in cooperation with the Wüstenrot Foundation, aims to draw attention to deteriorating buildings. Among them is the Central Animal Laboratory of the Free University of Berlin, also known as the "Mouse Bunker."

If there is no money for maintenance and renovation, an entire building can quickly deteriorate. The Brutalist St. Agnes Church in Berlin was such a case. In 2011, it was leased and renovated by Berlin gallery owner Johann König. Its distinctive architecture has been preserved and it is now home to the König Gallery.

The Helicoide de la Roca Tarpeya in Caracas, Venezuela, was to be a huge shopping center. Due to underfunding and political conflicts, construction was halted in 1960. In the 1970s, the building was illegally occupied and later used by the secret service as its headquarters. It is still partly used today as a prison for political prisoners.

Habitat 67 in Montreal, Canada, is one of the best-known Brutalist buildings. Architect Moshe Safdie designed it for Expo 1967 and actually saw it as a counter-reaction to Brutalism. It has been a listed building since 2009.