His approach has won him fame. Following the 1997 opening of the Guggenheim Museum in Bilbao, Spain, he secured the American Institute of ArchitectsÂ' Gold Medal of 1999.
Personally, he shuns the ostentatious. While he has also designed furniture and dabbled in real estate, he says what he really longs to do is build himself a little cabin - if he could only find the time.
In this interview, he conceded he has a second sense about finances - in his office and in the marketplace.
From whom have you learned important lessons about money?
I just made up my mind a long time ago that I don't borrow money. And I pay everyone that works for me. I started my practice without a lot of money and managed to follow that rule since 1962. And we have 120 people now and I still live by those rules.
Do you think anything's changed about the role of money in our lives?
Well, money is power. I don't think about it a lot. As I'm getting older I'm thinking about leaving money to kids. I don't spend a lot of money and I don't need a lot, personally. I don't live in a fancy way.
Has anything changed over the years in the role money plays in your life?
Well, I feel secure (laughs) - the best you can say about that. I could stop work and be OK.
But you don't; you haven't.
No, because I don't know what else to do. I just work because I like it and people pay money for it. I mean if they didn't, I wouldn't work I guess. (Laughs.)
I don't have any real money philosophy or anything. I sort of watch the stock market. I'm interested in the fluctuations but I don't really understand it.
We have money in the stock market and I have advisors, an accountant, who helps me with that. But I don't pay much attention. Occasionally, I have a project I'm working on when I get all excited about what they're doing. I call up and say, "Buy some stock in this place." And then they never do it. They always have some reasons.
I'm not naïve. I have to make buildings on budget. I worry about clients' money a lot. I have to worry about making sure they get their money's worth.
IÂ've noticed a contrast. Some of the buildings you've designed are quite costly. Like $100 million for the museum in Bilbao. And yet you tend to like to work in industrial blue collarÂ…
They're not different tendencies. They're one. Bilbao was under $300 a square foot, which is a very inexpensive building. But it's a big building - that's why it costs so much.
When I do a house for a rich client, I tell them I'm going to make them a middle-class house because it's not going to be a house with marble. I'm not very good at that part.
So you use kind of unconventional materials?
Yeah, I mean it doesn't have to be chain link and corregated. But I don't fuss with a lot of fancy anpretentious and ostentation. I wouldn't be able to do a house for somebody that wanted that.
Do you have any financial advice for younger people?
A banker years ago when I was going in to buy a house said if you believe in yourself, invest in yourself. And I thought that was good advice and I followed it. If you really believe in something, you find ways to make it happen.
When I was doing the cardboard furniture years ago, I never intended to go to the market with it. But some very wealthy guy from New York saw it and wanted to invest in it. I didn't have much money at the time. When you're creative and you do things, people are interested.
The projects that I do - they're not for everybody. I have enough clients to keep me busy. But it's not rampant.
Now there's all kinds of talents of architects or artists. Some of them are less public, more technical, theoretical. If I was just theoretical and did that, then I would end up teaching and being at the university and writing books.
I'm more hands-on, working with materials, less about theory, more about building. I mean I get excited about the interrelationships with the people I work with and in the making of projects. So I follow that course and people get involved.
It was observed that you like to continue thinking about a project even after it's built. Does that apply to your style of managing money?
I don't understand the stock market. I wouldn't know which ones to buy. My guy has me 60/40, 60 in bonds and 40 in stocks. I was told that's a very conservative position. And they think that's what I should do at my age. I don't have any basis for contradicting it.
Every day in the morning when I get up and go for the news, I always look for what the stock market's doing; it's just a habit. Generally to watch the growth in the country has been interesting to me.
You choose to live modestly.
I wouldn't know how to do the other. I'm not that interested in a big mansion. I mean I'd like now to build a little house, another one.
We have a little lot in Montana that I've been trying to build a little cabin on for 10 years. And I haven't been able to do that. It's just the shoemakers' shoes thing. You don't have time for yourself.
You invested in real estate - for a while?
A little bit. I still own a few things but I'm trying to get out of it.
What would you say your biggest financial mistake has been?
[Being] overly optimistic about some of the real estate things that I went into.
What would you say your best financial move has been?
Well it was real estate, too, actually. One of those properties I sold and it paid off. I didn't develop it myself. I sold it to somebody.
Any sort of overall observations about the role money plays in our life?
If you spend all your time counting and worrying about it, unless that's the thing you do in life, it's not very nteresting. So I focus on what I do, and the money comes as a result.
Any insights about the way Americans in particular view money?
I tend to hang out with artists and creative people. The people I know aren't the kind who flaunt their mansions or are pretentious.
But I work with a lot of business people who are very focused on money. They're always talking about bottom line. And I respect that. That's their business. And I do projects for them.
I know how precarious they are. There's lots of stuff riding on those investments. And my architecture is only a small part of it.
If money were no object, what project would you design? What would you build?
I don't know if I would be any good in that. You know, I've had a few people come in and offer me projects with no constraints.
The best work is done with constraints. So I don't think it's necessarily the greatest thing to be given an unlimited budget.
There are some things that I do that I don't think about budget at all until down the line. But they're theoretical, experimental and exploratory. So I try to wait and see where it goes. But I always have a second sense about the finances somehow.
I have a real good sense of the business end of my office. And I run it like a very tight ship. But I don't run it personally. Last year we grew and I sort of lost track a little bit. And we grew too fast.
And I could feel when that peripheral sense wasn't clear. And I called in everybody and regrouped and said, "Look, I'm not sure where - I don't feel right yet." And then we put in all the controls and stuff so that I got myself comfortable.
Since I don't have any rich relatives I know that if we got in trouble, I'd have to sell my house. (Laughs.)
Marjorie Backman is a copy editor for CBS.com