His mission was to immerse his art in the "curved universe of Einstein."
Niemeyer is best known for the breathtaking, unsurpassed architectural symphony of the buildings he designed for Brazil's capital - edifices he hoped "have perhaps given ordinary people, powerless people, a sense of delight. That is what architects can do."
And he was a lifelong communist.
As his friend the Uruguayan writer Eduardo Galeano remarked, "Niemeyer hates capitalism and the right angle.
"There isn't much he can do against capitalism, but against the right angle - the oppressor of space - his free and sensual architecture triumphs weightless as a cloud."
But Niemeyer wouldn't have agreed that there wasn't much he could do about capitalism. He joined the Brazilian Communist Party (PCB) in 1945.
"I understood right away that we had to change things," he once said. "The path to change was the Communist Party. I joined the party and have remained in the party, following all the ups and downs that life has imposed."
This included persecution and exile that only tempered his dedication to the struggle for social justice. His commitment was not shaken by the fall of Soviet socialism - he became president of the PCB in 1992.
Brasilia is his most prominent legacy. Brazil's progressive president Juscelino Kubitschek decided to move the country's capital from Rio de Janeiro on the coast to its central highlands in 1956 to encourage more even economic development.
He invited Niemeyer, a friend of his, to design some of its most prominent structures, including the presidential palace - where he was lying in state last week - the Congress building, the Palace of Justice and the cathedral as well as many blocks of flats.
Brasilia was completed in just four years. It now has a population of 2.2 million - making it the largest city in the world that didn't exist at the start of the 20th century - and is designated a Unesco world heritage site.
His fortunes changed after the military coup in 1964. As an outspoken communist, his offices were raided and his work was halted.
He went into exile the following year, settling in Paris - where, among other things, he designed the headquarters of the French Communist Party.
As he told that party's newspaper l'Humanite, "There are too many injustices. But commitment to the Communist Party provides hope, solidarity and the realisation that it is possible to struggle together for a better world."
His architectural achievements continued throughout his life.
In 1988 he was awarded the Pritzker Prize - a sort of Nobel for architecture.
In 2003 he astonished London with his Serpentine Gallery Pavilion, which one critic described as a "time-warping miracle."
Built in steel, concrete and glass, its elevated structure afforded the partly submerged auditorium full-circle vistas across the park.
Until earlier this year he continued to work on new commissions in his office overlooking the Copacabana beach in Rio, hosting weekly political discussions and welcoming visits by friends.
In all he designed over 600 buildings around the world. At his death Brazil's President Dilma Rousseff said: "Brazil has lost one of its geniuses. It is a day for crying."
Oscar Niemeyer is survived by his wife Lucia Cabeira, whom he married in 2006, as well as five grandchildren, 13 great-grandchildren and seven great-great-grandchildren.
His wife of 75 years, Annita, died in 2004, as did their only daughter Anna Maria aged 82 earlier this year.
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