Oscar Niemeyer, one of the 20th century’s most important architects, who designed the United Nations building in New York and his country’s futuristic capital of Brasília, died on Wednesday in a hospital in Rio de Janeiro. He was 104.

Supreme Federal Court Brasilia

Supreme Federal Court building, Brasilia

Niemeyer began his career in Rio de Janeiro in the 1930s as a pupil of Lucio Costa and the Franco-Swiss modernist pioneer Le Corbusier. Costa later became his partner in the creation of Brasilia.

Museum of Contemporary Art Rio de Janeiro

The Museum of Contemporary Art near Rio de Janeiro

Brazilian President Dilma Rousseff, whose office is located in Niemeyer’s Brasilia buildings, paid tribute to the architect, calling him “a revolutionary, the mentor of a new architecture, beautiful, logical, and, as he himself defined it, inventive.”

Brasilia cathedral

Brasilia’s cathedral inaugurated in 1960

Niemeyer won the 1988 Pritzker Architecture Prize, considered the “Nobel Prize of Architecture,” for the Brasilia cathedral. Despite the fact that most of the structure is underground, the “Crown of Thorns” cupola brings the church light and loftiness.

Brasilia National Museum

The ramp of Brasilia’s National Museum

Built in the space of just four years, the collection of public buildings in Brasilia is perhaps the architect’s main achievement. The city opened in 1960.

Brazilian Congress Brasilia

View of the Brazilian Congress in Brasilia

Described today as “retro-futuristic,” Brasilia has also been qualified as poetic and monumental.

French Communist Party headquarters

French Communist Party’s headquarters, Paris

A longtime communist, Niemeyer designed the French Communist headquarters (1967-81) during a period of exile that he spent in France.

Maison de la Culture du Havre

Le Volcan at the Maison de la Culture du Havre, France

This structure (1972-83) reveals Niemeyer’s signature use of concrete in curvaceous forms. The architect designed 600 works around the world and had some 20 other projects under way.

United Nations building

The United Nations building in New York

Niemeyer’s creation has served as the official headquarters of the United Nations since its completion in 1952.

Auditorium Oscar Niemeyer Ravello

Auditorium Oscar Niemeyer, Ravello, Salerno, Italy

Oscar Niemeyer’s all-white design is situated on the Amalfi Coast and, at 365 meters above sea level, offers an impressive view of the coastline.

Oscar Niemeyer International Cultural Centre

The Oscar Niemeyer International Cultural Centre, Avilés, Spain

Inaugurated on May 26, 2011, the center was one of the architect’s most recent projects. Niemeyer described it as: “An open square to the humankind, a place for education, culture and peace.”

Headquarters of newspaper L'Humanite

Headquarters of newspaper L’Humanité in Saint-Denis, north of Paris

The building was designed and constructed in 1989 for French Communist newspaper L’Humanité.