We mustn't forget the emotional impact of the buildings around us
Many people don't see architecture as important, even very smart people. They leave it to somebody else.
But to me, there's nothing more important than architecture. It creates your world and influences how you feel both mentally and spiritually.
So, if you live in a horrible place, you'll be impaired mentally. Let's say you live in a dark environment with no windows and with nothing but a blank wall behind you. You'd be in a prison, and that would have a detrimental impact on your mental health.
The most neutral architecture is often the most aggressive. But in buildings that move us, there's an element of care. It's not a question of whether a building makes us feel good or bad. It's about being moved. That's what the word emotion means. What we feel is the sense of intensity, passion and involvement. It's something that goes very deep.
Look at a Frank Gehry building, for instance, and you can see the love and care and infinite labor it took to bend that piece of steel. You can see it in high-tech architecture like that of Norman Foster, the love for an incredible suspended piece of glass and how difficult it is to make a piece of glass look like it's floating. It's also why people love going to old medieval towns or beautiful villages -- because they inspire us to feel moved.
In great cities, the great buildings tell you things you don't know and remember things which you've forgotten. It's a collective wisdom, an engine superior to your own intelligence. Architecture is the biggest unwritten document of history.
We are certainly writing a new chapter today. Places that were just caravans in the desert are suddenly high-density cities with incredible buildings. Cities that were neglected are now competing with other major cities: Shanghai vs. Beijing, Beijing vs Frankfurt, Frankfurt vs. New York. Nobody could have predicted 50 years ago that it would be cities competing with each other rather than nations.
And it's important for a city to have incredible variety. I don't like oppressive cities that offer no relief. We see this in authoritarian attempts at controlling architecture, whether it was enlightenment thinkers or Stalin or Hitler or Mussolini. They tried to rebuild the world in their image, and their idea of playing God failed because of our irrepressible individuality.
I often wish the city was more creative, that the sidewalk was a more fantastic experience, because life is short and you don't want to walk through a dull-witted place. The great cities we really admire have this perplexing variety of thoughts, forms, colors, dialects, spiritual ideas.
As an architect, it's my responsibility to make a personal connection -- not just with the physical environment but how it triggers our memories and emotional responses.
When I explored the site for the Jewish Museum in Berlin, I put myself into the souls of those who are not there, into the emptiness I felt. I tried to see how it would feel to be there when you're not there. What does it mean to create a space for those who were murdered, who disappeared in the smoke?
You could feel that emotion here in New York after 9/11, the souls of those who are lost at ground zero. You don't have to be a mystic or religious in any way. Everybody would feel it.
You come to the bedrock, the slurry wall, the emptiness, and you are suddenly enveloped in a space that isn't just what you see on the ground. You're in connection with this place and its history, and that connection speaks to you.
It tells you what the limits are, the taboos. You cannot treat it as if you were just walking on another kind of ground. This place is unique. There is a delicacy about it that has to be protected. That's all part of exploring the site. I would call it a spiritual journey.
Even with a regular site, you have to be interested in it and sensitive to it. If not, you can do whatever you want. Architecture is already violent -- you always have to dig a foundation -- and we can tell when somebody does something just for a quick buck. We can feel that carelessness and the silence it produces.
When I first came here in 2001 it was a ghost town. Once in a while I would see two or three people standing in the rain looking at the site.
Every day I have seen this site transform itself, but transform itself with a memory -- not by hiding what happened.
The talk about ground zero also changed very slowly. It was like something coming up out of an abyss, not different from my experience in Berlin.
When I started working on ground zero, the developers were speaking of large floor plates for trading floors, and my idea was very different — that this is not going to be Wall Street again, it's going to be a new neighborhood.
To me the proof of its success is how many people have moved into that neighborhood. A hundred thousand people have moved to Lower Manhattan since I started working here. It's a rebirth of a zone of a city that was very functionally Wall Street. Now it's a place for creativity.
There are both the profane and the sacred in architecture. But sacred does not preclude celebration. So eating an ice cream or even throwing a Frisbee at ground zero is not in contradiction with the space, because it's the space that allows you to do certain things.
It takes a long time for a public space to shape itself. For ground zero, it's taking more than two hundred years. At first, New York was just a few streets laid out on a map. But incarnated in that initial gesture was the spirit of this island, this tip, jutting out into the world. A spirit of the unexpected.
That's the optimism that is lodged in every gesture of architecture. The metaphor of life is rooted in architecture. To be born, to grow, to be, is an architectural experience. It starts from excavation, from nothing, and has only a plan that in time comes to fruition. No matter how sad, how tragic a site might be, how abused by history, architecture has the notion of a future.
That sense prevents it from being something in a minor chord. Even erecting a monument to the dead, in any form -- writing a book or planting a flower or a tree -- has a sense of hope and redemption.
To me, that is the emotion of architecture.
As told to CNN's Steven Goldberg. Video by CNN's Tawanda Scott Sambou.