BRASILIA, Brazil -- Hundreds of mourners lined up in the vast open plaza at the heart of Brasilia, Brazil's modernist capital, to honour internationally renowned architect Oscar Niemeyer during a Thursday memorial in the city that most strongly reflects his signature style in its monumental buildings of flowing concrete and grand, sweeping curves.

Niemeyer's remains were flown by presidential plane to the capital from his native city, Rio de Janeiro, where he died Wednesday night at age 104. Elisa Barboux, a spokeswoman for the Hospital Samaritano in Rio, said the cause of death was a respiratory infection.

Elegantly attired in a black suit and matching hat, Jose Grilo, 70, was among those lining up to honour the architect who brought grace and flow to a city erected on an immense arid plain. His parents were labourers, two among the droves of Brazilians who flocked from all over in 1960 seeking work and a better life in the brand new city.

"I grew up seeing these buildings and always admired Niemeyer," said Grilo. "I always dreamed of meeting him in life; now I can see him in death."

After the flight in the plane loaned by President Dilma Rousseff, the remains of the groundbreaking architect rested in the presidential palace, a deceptively simple building of glass and concrete that seems nearly weightless, an airy glass structure held aloft by vast, curving white pillars. Immense white ramps unspool from within the structure. It was on the main walkway that the mourners marched in to see the creator of these quintessentially Brazilian forms.

A young architecture student, Daniela Menezes, also in the long line, saying Niemeyer was an idol and the reason why she wanted to become an architect.

"I grew up in Brasilia, and have great pride in this admirable man," she said.

As an artist, Niemeyer favoured cold concrete and glass, but as a man, he was regarded with great warmth by the population. This affection was visible as the funeral cortege paraded his remains through Brasilia, between the airport and the presidential palace. People simply stopped what they were doing and applauded.

After Thursday's vigil and public visitation, his remains will be returned Friday for burial in Rio, where the governor, Sergio Cabral, has called for three days of mourning.

"His manner was gentle, his convictions were firm, and he was loved by the Brazilian people," Cabral said in a statement.

Born into an elite family, Niemeyer was a lifelong communist who took a stand against social inequality in one of the most unequal nations on Earth, though he held no illusions his work could create a more egalitarian nation.

Rousseff described Niemeyer as "revolutionary," saying in a statement that he was "the mentor of a new architecture that was beautiful, logical, and as he himself defined it, inventive."

Sergio Magalhaes, president of the Brazilian Institute of Architects, said: "Beyond being an architect, Niemeyer was a man ahead of his time, who stood in solidarity with the people and who was loved as few have been."

In works that ranged from Brasilia's crown-shaped cathedral to the undulating French Communist Party building in Paris, Niemeyer shunned the steel-box structures of many modernist architects, finding inspiration in nature's crescents and spirals. His hallmarks include much of the United Nations complex in New York and the Museum of Modern Art in Niteroi, which is perched like a flying saucer across Guanabara Bay from Rio de Janeiro.

U.N. Secretary-General Ban Ki-moon said Thursday that Niemeyer's work in designing the United Nations headquarters complex "stands as his legacy to the world."

The U.N. chief called Niemeyer "a towering figure" who was outstanding not just because of his stamina and talent but because "he imbued his work with a powerful sense of humanism and global engagement."

Niemeyer was one of a group of internationally renowned architects, including France's Le Corbusier, who designed the iconic 39-story U.N. complex that is now undergoing renovation.

"Right angles don't attract me. Nor straight, hard and inflexible lines created by man," Niemeyer wrote in "The Curves of Time," his 1998 memoir. "What attracts me are free and sensual curves. The curves we find in mountains, in the waves of the sea, in the body of the woman we love."

His curves give sweep and grace to Brasilia, the city that opened up Brazil's vast interior in the 1960s and moved the nation's capital from coastal Rio.

Niemeyer designed most of the city's important buildings, while French-born, avant-garde architect Lucio Costa crafted its distinctive airplane-like layout. Niemeyer left his mark in the flowing concrete of the Cabinet ministries and the monumental dome of the national museum.

As the city grew to 2 million, critics said it lacked soul as well as street corners, "a utopian horror," in the words of art critic Robert Hughes.

Niemeyer shrugged off his critics -- and kept working until the days before his death, with engineers visiting his hospital room to talk over pending projects.

His admirers said Niemeyer's work make him an eternal figure, whose influence on his nation won't fade.

"A few days ago, I heard something I really liked -- Oscar will never die," Paulo Enrique Paranhos, who leads the Brasilia branch of the Brazilian Institute of Architects, told the Globo TV network. "It's not an exaggeration for those of us who love architecture."