'How does a Parthenon really work?' Correa asks. 'It works because you are climbing up a hill to where the gods live. That's such a deep internal instinct'. Admittedly, approaching the Bhopal capital by road somewhat dispels that reaction.

The curved perimeter of the Vidhan Bhavan with its punched apertures foretells an aspect of Correa's most recent favourite, the Champalimaud Centre for the Unknown in Lisbon (see Blueprint July 2011). Correa described this biomedical research and cancer treatment centre, which includes a vast enclosed garden, as 'three stone ships sailing in a sea of granite'.

The Vidhan Bhavan in Bhopal is internally divided into nine compartments, like the Jawahar Kala Kendra. The 31m-wide, 25m-high dome covers the circular Assembly Hall

Here, Correa distills recurrent metaphysical elements - open to sky spaces and a ritual path, here leading to a vista of the ocean between columns. Champalimaud also encapsulates the spirit of the site; Christian Norburg-Schultz called it the 'genius loci', referencing the great Portuguese navigators who sailed from there into the unknown.

How did he deal with the genius loci of the narrow strip between Manhattan's 43rd and 44th Streets, site of his Permanent Mission of India to the UN (1992)? The red-sheathed 28 storeys are punctuated by great openings into verandahs-cum-atria, double-height in the podium and triple- height at the slim tower's summit.

The top of India's UN Mission in New York reveals an exciting 3D spatial array, including open-to-sky terraces under one of Correa's characteristic louvred pergolas

'The client wanted something that was as Indian as possible, he says. 'It is in Manhattan, but the building is not one that is American. Subtle, not an exotic one-liner - I didn't want to do kitsch.' Correa is no fan of 'this nonsense of the Big Apple', dismissing Central Park as 'just for Gene Kelly to dance in', and Manhattan as an 'over-high slum, degenerate, unaffordable, (for) very rich whites and poor condemned blacks... That's what's going to happen in Bombay, and we will be stupid if we do nothing about it'.

Practical solutions for the poor are a strong thread in Correa's work, even extending to redesigning the sidewalks of places such as downtown Mumbai in his Hawkers' Pavements design of 1968, even accommodating 'night-dwellers'. Cities are central to his work. 'Bombay is ruined by just being a bloody city about money,' he says, but in 1964 he started addressing a different problem - how the already-congested city left by the British could handle exponential population growth. 'When you know you're going to double, the advantages for that quantum leap will allow you to get your act together. You can reorganise', he says.

Correa proposed exactly that with his Bombay Plan (1970): to reorientate the entire exploding metropolis by building the satellite city of New Bombay on the other side of Thane Creek. Now called Navi Mumbai, it is the world's largest planned new town, with more than a million people. Although Correa is still surprised by the progressive optimism shown by the government in accepting and building his proposal, he says they ' did it badly because they did it themselves'. Now Navi Mumbai is just a part of the Greater Mumbai metropolitan conurbation of 20 million. Nevertheless, Correa was addressing the issues of the exploding megacity decades before it was on the mainstream agenda. In 1985, prime minister Rajiv Gandhi appointed him to head the National Commission on Urbanisation, and in a period of two years he visited every state in India, identifying 329 towns growing faster than average, and incidentally seeing Bangalore, now India's IT capital, as a special case because of its cool climate and cantonment structure.

In 1964, Mumbai (then Bombay)'s population had tripled in population to 4.5 million in just 30 years. Anticipating yet more explosive growth from then, Correa, with Pravin Mehta and Shirish Patel, drew up a plan to re-orientate the chocked north-south conurbation by building a new Navi Mumbai across the creek, and exploiting water for transport

Despite the mixed success of Navi Mumbai, Correa is optimistic about cities, often relating the story of the washerman and money-lender sitting next to each other on a Mumbai bus, a social integration which might have been difficult to imagine under the traditional caste system. While he notes that 'working in India, the issues encountered are really heroic', sadly it's the Indian states that run the cities rather than elected, accountable mayors (with the exception of New Delhi, the political capital), and Correa finds it difficult to maintain hope '...when I think of the way the political parties are exploiting our cities for money'.

There is both a profound humanity and sense of the metaphysical in Correa's work. He laments that 'architecture has become fashion' and the 'tragedy of architects is we know how to do everything and nothing'. Correa's architecture certainly transcends fashion, and spans the universal... and the void. His own career across five decades mounts a formidable narrative, running from Gandhi-like simplicity to state-of-the-art research centres. He has reinstalled the cosmos into architecture yet designed for those who sleep beneath the stars, and has tackled issues of sustainability and developing-world urbanisation before the terms were even coined.

His best projects make even works by Pritzker winners look trivial, parochial or dated in comparison. With his gift to the RIBA - and by digital extension, to the rest of the world - Correa leaves one of the world's great and hitherto unsung architectural legacies.

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