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."
Associated Press writers Bradley Brooks in Sao Paulo and Juliana Barbassa in Rio de Janeiro contributed to this report.