At home, I have a wife, fortunately, and my children are all grown, and I have many grandchildren. I spend weekends with my grandchildren; I adore them.

I travel to the Middle East, I travel to China, I travel to Europe. It's all very rewarding - the only problem is the travel is getting more and more difficult for me now. Ten years ago I would have enjoyed it a lot more.

Qatar does not have much history, it's a new emirate. So I couldn't draw on the history of the country; its history is really just being a desert. But I thought, the one thing I must learn about for this project is the Islamic faith. So I read about Islam and Islamic architecture, and the more I studied the more I realized where the best Islamic buildings were.

I believe that architecture is a pragmatic art. To become art it must be built on a foundation of necessity.

At the beginning, I thought the best Islamic work was in Spain - the mosque in Cordoba, the Alhambra in Granada. But as I learned more, my ideas shifted. I traveled to Egypt, and to the Middle East many times.I found the most wonderful examples of Islamic work in Cairo, it turns out. I'd visited mosques there before, but I didn't see them with the same eye as I did this time. They truly said something to me about Islamic architecture.

You cannot defend your design without knowing what you're designing for.

Many of the projects I'm most proud of are tall buildings, especially the housing projects. In New York I have two: one in Kips Bay and one at New York University. At that time, those projects were most challenging.