From ten floors up, the view through the living room's curved Modernist windows is sublime. There is a velvety band of sea - imagine Quink royal blue ink on blotting paper - and then the switchback of the Tiririca hills whose sinuous profile smudges into the pearly heat haze. It's hot in the penthouse, and the noise of the traffic gargles upwards from the Avenida Atlantica. The view is highly significant, but nobody here is looking across Rio de Janeiro's Copacabana beach towards the dazzling horizon.
There is something else to consider. A short, slightly-built 95- year- old is standing at a drawing board. He's immaculate: razor- creased slacks, crisp white shirt through which dark blue braces can be seen, and scrupulously pulled up socks rising from beautifully made cuban-heeled loafers. He holds a carefully poised cheroot in one hand and a chubby magic marker in the other, as if it were a paint brush. And he is talking quietly, repeating what he has undoubtedly said hundreds of times before, as if reciting a rosary - a special anti-rosary, mind you, available only to those who have been atheistic communists for more than half a century.
His sentences are translated rapidly by an intent young assistant, and on the floor by the young man's feet lies a jumble of abandoned A2 sheets of tracing paper, perhaps a couple of dozen of them, covered in curvaceous lines and occasional tremulous squiggles. It's the work of the last, and indisputably great, figure of mid-20th century architectural Modernism, the man so brilliantly chosen to design this summer's pavilion for London's Serpentine Gallery.
His name is Oscar Niemeyer, and he delivers a sideways glance, steady- eyed. "When I designed Brasilia, I began with the cathedral," he murmurs. "I was not concerned with how cathedrals had been made before. And I don't believe in anything, but I tried to feel like a catholic when I was designing it." He waits for the laugh, which he gets, and moves on, talking steadily and obdurately in a two hour long riff about spans and cantilevers, the poisonous effects of computer-aided design, the rumour that he had described the "unintelligent" George Bush Jr as a son of a bitch, and that one good but entirely temporary solution to the intractable absurdity and misery that he insists dominates existence is to spend time on Copacabana beach with a beautiful girl.
This whistle-stop litany is not offered as good copy (though it certainly is), but as a sampler of the architect's outpouring of dreams and protest. Niemeyer is not a schmoozer; he despises "boring social affairs dripping with lies and hypocrisy". And his singularity, and talent, was obvious from the beginning.
Le Corbusier, the architectural genius and polemicist, was so wary of the young Niemeyer's skills that he prevented the Brazilian's design for the United Nations complex - unanimously favoured by the judging panel - from being selected ahead of his own in 1954. "When he saw the presidential palace at Brasilia," says Niemeyer, "he said it was beautiful. He said it was highly intelligent. But I was not fooled by this comment - it was just the politics of being neighbourly. Le Corbusier is a major figure, but a small architect." He delivers that subtle sideways glance again, pauses for a couple of beats and adds, smiling: "That last remark was not ethical."
Hugely talented and sharp, then. But why else does the designer of this year's Serpentine Gallery pavilion deserve particular attention? Cynics might say that it's because he's venerable and legendary, an echo from the epigraph of TS Eliot's poem, The Hollow Men: "Mistah Kurtz - he dead. A penny for the Old Guy." And, after all, the designers of the gallery's first three pavilions were (assume casually ironic voice at this point) like, majorly serious: Zaha Hadid, Daniel Libeskind, Toyo Ito. What can we say? So, now it's Niemeyer. …