Talk about beauty and you get boring answers, but talk about ugliness and things get interesting.

Lagos has also had a particular effect on my career. I was there early, and although it was a courageous step to go there and invest on this scale - I went there maybe 20 times - it's also been also super-controversial. There's an old school of thought that somebody like me has no place to go there.Because of colonialism and so on.

Criticism per se does not worry me. I've always solicited it as part of the design process.

I studied in London in 1968. Our school had a separate department of tropical architecture. Of course it was totally unfashionable, partly because nobody wanted to think about colonialism, but basically what you learned there was that, OK, the sun is here, so you should create natural ventilation here - an unbelievable amount of really sound principles that have been completely abandoned, so now everything is air conditioned with big machines.

What is now called "green architecture" is an opportunistic caricature of a much deeper consideration of the issues related to sustainability that architecture has been engaged with for many years. It was one of the first professions that was deeply concerned with these issues and that had an intellectual response to them.

Nigeria was a blank on the map - there weren't even any maps. The US State Department, everyone said don't go there. It was courageous of Harvard University: the notion was that we would match Harvard students with Nigerian students, so that every student would have a guide, creating a guarantee of intimacy with the city.

Our society can no longer tolerate ugliness. You see that in cars, sofas and women. [But] ugliness also has a right to exist.