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Bank of China Shanghai Free Trade Zone Mixed-Use Development, Shanghai, China, by Didi and Sandi Pei

After his retirement, I.M. Pei continued to work as a design consultant with his old firm. The studio was involved in such projects as the Rock and Roll Hall of Fame in Cleveland (1995) and the German Historical Museum in Berlin (2003). Alongside these occasional commissions, he embarked on meaningful collaborations on projects with his sons: The dearest and most special of them was the Suzhou Museum (2006), which was built within a short walking distance from Pei’s ancestral home in the historical heart of Suzhou. 

Pei’s sons, in fact, have been running their own company for 30 years. Chien Chung “Didi” Pei (b. 1946, Boston) and his younger brother Li Chung “Sandi” Pei (b. 1949, New York) are the founders of PEI Architects in Manhattan. They founded their practice, formerly Pei Partnership, in 1992, two years after their father retired from a full-time practice from his office, Pei Cobb Freed & Partners, where the brothers had worked since graduating from Harvard GSD, with Didi contributing to the design of the East Wing of the National Gallery of Art in Washington, D.C. (1978), the Grand Louvre in Paris (1993), and Fragrant Hill Hotel in Beijing (1982), the first modern project in China designed by a western architect. In his own right, Sandi played a leading role in such projects as the MIT Arts + Media Technologies Facilities in Cambridge, Massachusetts (1982) and, more prominently, the Bank of China Tower in Hong Kong (1990).

Among their own firm’s standout projects is the Bank of China’s Head Office Building in Beijing (2001). Sandi is now working on three additional projects for the bank, comprising a total of about five million square feet across regional headquarters in Shanghai, Hainan, and Nanning, which continues his family tradition (I.M. Pei’s father, Tsuyee Pei was the general manager of the Bank of China). Additionally, there is a boutique hotel in Fuzhou, the capital of Fujian province, and a 60-story residential tower in Toronto nearing completion. And Didi just finished a winery in France and a high-rise office building in Brazil, and is now working on a 3.5 million square foot high-tech campus in Beijing for China’s leading construction-equipment manufacturer SANY.

Sandi and Didi Pei
Chien Chung “Didi” Pei (right) and Li Chung “Sandi” Pei

I met with the brothers at their high-floor spacious office on Park Avenue South with expansive views over the Hudson River along Manhattan’s west side. Our conversation, which follows in a concise version, took place inside a square windowless room lined on every side and from floor to ceiling with up-to-date professional magazines and books. We talked about some of I.M. Pei’s most critical projects, lessons learned from studying at GSD, the power of geometry, how the brothers started their own practice, and the need to look at architecture as a continuum, like a tree that grows from a single root with limbs and branches.

Vladimir Belogolovsky: I came across a New York Times article from December 14, 1964, the day the Kennedy family announced the selection of your father to design the JFK Presidential Library. At the time it was arguably the most sought-after project. How do you remember that moment: was that before both of you went into studying architecture?

Li Chung “Sandi” Pei

Yes, it was perhaps the most highly anticipated commission at the time and involved a competition of some of the leading architects, including Mies van de Rohe, Kenzo Tange, Basil Spence, and Louis Kahn. It was announced in December 1964 but we first became aware of the selection while we were on a family trip to Italy in July when a telegram arrived notifying our father to expect a call and requesting a time and a number where he could be reached. The call was taken at the local post office where we all went, and we were so excited. The news was delivered by Bill Walton, the Chairman of the Commission of Fine Arts and a close friend of the family. He managed the selection process. So, we knew the decision months ahead of the announcement. I was in my first year at Middlesex, a boarding school in Concord, Massachusetts, when the announcement appeared on the front page of the New York Times. It was a turning point in my father’s career, and, of course, a proud moment for me personally.

Was that the moment when you said to yourself, “That’s what I want to do – I want to be an architect”?


Oh, no. That came much later. In fact, as an undergraduate at Harvard, my focus was on attaining a broad liberal arts education, not a future professional career. I have always been interested in the arts and selected as my concentration visual and environmental studies, where I took classes in painting, film, and art theory among others. I didn’t take an introductory course in architecture until my junior year and fared well enough that my professor asked me to be his teaching assistant for the next semester and, subsequently, he wrote one of my supporting letters for graduate school.

Chien Chung “Didi” Pei

For me, 1964 was the year when I was just starting college and architecture was not something I was going to pursue. In my undergraduate years at Harvard, I studied physics and math. We were required to take very different courses for a well-rounded education and that’s how I ended up taking architectural history. The main reason for that was our family trips to Europe – we went on two extensive all-summer trips. One was to France when our elder brother finished high school, one year before I did. And then to Italy right after I finished high school. But our father did not really share with us what he was doing professionally. He never pushed us into anything. So, it was only when I went to GSD that I finally committed to architecture. I must add that I was somewhat disappointed there. 

Because of your professors?


Most of them were not practicing architects. There was no training for professional practice. So, every time there was a new critic who was a practicing architect I would sign up for the course. I did not like theory. [Laughs.]  

Bank of China, Suzhou, China, 2015

Which professors influenced you the most?


I had a great professor, Gerhard Kallmann. He and his partner, Michael McKinnell, had designed the Boston City Hall about a decade earlier. I agree about not being able to learn enough about the profession from our instructors, many of whom had minimal exposure to the actual practice of architecture. If you ask me what I learned from my professors, I’d have to say that I had to discard more than what I learned. When I arrived, I thought I knew architecture. Of course, I didn’t. But I was the son of I.M. Pei, how could I not know?! [Laughs.] So, I came with all sorts of preconceptions that during my first semesters my professors sought to expunge with often harsh criticism of my instinctive but rather superficial design approach. It was like a boot camp, a hazing of sorts. And to be honest, they were right.


I was taught both by Kallmann and McKinnell. They were my favourite professors precisely because they were practicing architects. Then one year, Paul Rudolph came. I took his course, which was OK. But then Charles Gwathmey came. He was very good. He taught me that you need to know what your idea is. And then every decision you make should make that idea stronger. That’s the design strategy – you pick a good idea and then keep reinforcing it. I learned it from him then and I still use it today. A good concept is half of your project. If the concept is not strong the project could never work. You must have a good direction. How can you learn this from a theoretician?!

Chateau Lynch-Bages Winery Pauillac, France, 2020

Both of you started working at your father’s office immediately after graduating from GSD. Did you make that decision at your father’s urging?


I had a short internship during one of my summers in Boston. My intention after receiving my degree was to work for Arthur Erickson, who was the guest critic at one of my reviews and later offered me a job in Vancouver. I admired his work and considered the opportunity as a way to avoid working for an American firm that might be a competitor to my father’s. Canada was a different place, yet close both geographically and pedagogically. My plan was to start working at his firm in the fall.

And then my father said, “But, what are you going to do during the summer?” I didn’t know, so he said, “I have this project, why don’t you keep yourself busy with it?” It was a Buddhist monastery in Upstate New York. It was small but very intriguing. I started working and guess what?! [Laughs.] By the fall it was still very early in the design process. So, I didn’t want to leave it. Did he offer me that job to keep me from going to Canada? I’ll never know. Unfortunately, it did not get built after all. But soon other projects came.


In my case, I wanted to work with my father right away. I felt I spent too much time at school. And the first project I started working on was the National Gallery of Art in Washington, DC. It was the key project at the office at that time. I never really worked for anyone else – except for one summer before my graduation when my father sent me to Taiwan to work on the exhibition for the Taiwan Pavilion, which he designed for the 1970 World Expo in Osaka. I spent my whole summer there working on collecting material for the exhibition, particularly on filming many beautiful places in Taiwan for the main film at the pavilion. It was all shot from a helicopter, and I was in the helicopter as the cameraman. It was such a wonderful summer. So, I didn’t really work for other architects, and even in my father’s office, I did not work with other partners either.

Didi, you served as a project architect and designer-in-charge for Fragrant Hill Hotel in Beijing. Finished in 1982, it became an important milestone for Chinese architects because it was the first chance for a leading international architect to build in modern-day China with an expectation of the first uncompromisingly modern building there. But the result was a disappointment for many locals who felt that the architect was too careful by producing a hybrid – half traditional and half modern. How do you see it? 

Edificio Adalmiro Dellape Baptista Faria Lima B32, São Paulo, Brazil, 2021

That’s a justified criticism today. But my father felt that you must go step by step. It was a difficult building to design. And don’t forget, it was the time when Post-Modernism became the latest fashion in the profession, at least in America. The work of Michael Graves, of course, is a good representation of that period. Before this building was built, Chinese architects followed the Soviet model. Chinese architecture was all stylized and preconceived. The purpose of making that building was not to demonstrate to Chinese architects how to do their architecture but that it was important to do a kind of architecture that could be identified as Chinese.

In the beginning, my father was asked to design a high-rise hotel in the centre of the city. At that time, most buildings were just a few stories high. So, he refused; he did not feel it would have been appropriate. Then he was offered different sites. He rejected all urban sites until the appropriate site on the outskirts of Beijing was offered. This commission was very important to him and he wanted to do it right. 

As far as the building’s plan it was done the way we do all our buildings. First, we try to establish a module. You may not see it but that is a rigorously designed modular building. It has a very strong geometry but every time it nears an existing tree, including a few 800-year-old trees, it goes around it. We played with the modular to follow this very basic idea in the most rigorous way. The whole justification for the design was to keep all those trees and small hills on the site. Fragrant Hill sits in the former imperial hunting grounds. And the facade design was quite traditional. You are right about everyone’s expectations of a truly modern building. But that’s not what he wanted to build there at that time.

Sandi, you spent eight years helping your father design the 72-storey headquarters for the Bank of China in Hong Kong, which when completed in 1990, became the tallest building outside of New York and Chicago. Could you share your insight on that process?


I had not done an office building, let alone a high-rise before the bank project. And what an honour it was for my father to design it, especially since his father was the bank’s manager for many years and initiated the construction of the old Bank of China building in Shanghai in the 1920s. I started from the very beginning when the idea first emerged. It was in the fall of 1982 soon after the opening of Fragrant Hill Hotel. On our way back to the States, I remember that we stopped in Hong Kong for two to three days of meetings. The bank had acquired one of the few remaining open sites in the central business district, a parcel that by happy circumstance lay just outside the airport flight path that permitted the construction of tall buildings. 

In late fall we were at our family country house when we began to design. Well, he started to design. [Laughs.] That’s when the idea came out: first the square plan, then the diagonal lines, etc. I made a study model lacing grey tape up the tower form. He asked me to make four loose sticks and start playing with them diagonally by going up and down until we locked the final shape in place. Then we had the first meeting with the structural engineer, Leslie Robertson, in my father’s office. The rest has been well documented.

Where did that now iconic form come from?


That was always very hard to trace with my father. You keep working and then there is this eureka moment when the form comes – sometimes abruptly but inevitably. Again, what was interesting about his way of working is that he always wanted to hear from those who worked with him. He always wanted other people’s input and he would never tell people – do this or do that. In a way, he used people around him as a sounding board. But personally, I felt that he had tested his ideas in advance. He kept it inside of him. There was no sketch, but he had an image inside his head. And he tested his idea through discussions, sketches, models, and lots of questioning. So, in the case of the bank, I felt the idea of the “X” over the square plan was already in his mind. I saw him draw that for the first time, but I have a feeling the real moment came earlier, and he already knew what he was drawing quite confidently. 


He surrounded himself with people he knew well. They would be the ones to develop his ideas. He didn’t even have to finish his sketches. To him, it was geometry itself that was crucial to the development of his buildings. Expressing geometrical rigour was important. The rigorous geometry is the framework around which you then can create. That’s when the intuition comes in.


I believe the bank was the first project where 45-degree triangles made up the project. He used triangles before, but it was the bank project that was entirely driven by this angular geometry. That’s what drove his architecture – its discipline, rigour, and rationale, which is how he always thought. Yet, he never allowed himself to be a slave to geometry because buildings always have these poetic moments that need to be found or invented.

Let’s talk about the time when you decided to break away from your father’s firm and start your own practice. It was 1992, not a very confident time economically.


Absolutely. The economy took a nosedive. Just before that, I was very busy – running the Louvre project in Paris and the Mount Sinai Medical Center here in New York, the two biggest jobs in the office, and several smaller projects in America. Then, all of a sudden, these two projects stopped, and no other major projects were coming. I considered leaving the office before but for years I was going from one project to the next, which involved personal client relations, and it was simply impossible to leave. But at that point, I thought, if I don’t leave now, I will never be able to leave. Our father officially retired in 1990, although he was still there, transitioning the firm’s ownership, and it was quite clear to me that the other partners would want to run the place. I asked for his advice and he said he would help me to start my own practice. Then he said, “But you should take Sandi with you.”


And I was itching to leave as well. The Bank of China was already finished. And I had successfully completed a small office building in California. I felt I had enough experience to run projects. And I was beginning to imagine other options, especially since our father was leaving and I was in my early 40s. It was the time to make the decision – either to stay or leave. But honestly, I didn’t really know how to leave. So, when the proposal came from my father to join Didi it made a lot of sense.

Balai Pameran Islam Sultan Haji Hassanal Bolkiah Bandar Seri Begawan, Brunei, 2019

What was your first project and how did the opportunity come about?


It came through our father, who was asked to do a very large mixed-use project in Jakarta. He kept turning it down, but once we decided to start our practice, he spoke to the developer and agreed to oversee it if we executed it. He convinced the client that we were very capable of designing their enormous project! 


It was two skyscrapers and a low-rise building, all on a huge podium for a total of 3.5 million square feet. So, we hired 15 people and went to work. We worked on that project until 1997 when a major economic crisis hit Asia and stopped the project, and sent our client into bankruptcy. By then it was already partially under construction, but it was never finished. 

There is a strong visual relationship between your work and your father’s. How intentional is this effort and have you ever tried to invent your distinctive style in opposition to your father’s?


We didn’t. I don’t think it is necessary to bring something entirely different. And if you look at the work, all our father’s projects are different, and all our projects are different. Of course, there is a strong geometry that’s evident, that’s foundational. It gives us discipline and architectural clarity. It allows us to keep discovering forms and spaces that are interesting; and by playing with them, we always respond to the context without imposing on it. We are working with modernist principles. There is always a system and rationale behind every design decision. Yet, we are able to deliver variety and surprises all the time.


Geometry guides our work. There is a geometric rigour and order that suggests the next step and provides options for how to break such order, which is always very conscious. Nothing is arbitrary. And relying on consistent geometry is what makes architecture economical. Repetition is a big component of our work. We try to avoid unnecessary complexity.

Bank of China Shanghai Free Trade Zone Mixed-Use Development, Shanghai, China, by Didi and Sandi Pei
Bank of China Shanghai Free Trade Zone Mixed-Use Development, Shanghai, China, 2023

Here is one of your father’s quotes: “Let’s do it right. This is for the ages.” Was that something he would say often?


He always looked at architecture as a continuum, like a tree grows from a single root with limbs and branches.


You see, he didn’t have to say it. He surrounded himself with like-minded people, and he developed a shortcut way of communicating his ideas with the team he worked with. He never preached anything. He developed a certain attitude, a language in his early work that would guide us on how to address new projects. Not many things had to be explained. There is a language in the work itself.


There are so many ways of doing architecture. Of course, what we do or what our father did is not the only way of doing architecture. But when you look at our father’s work, what comes across is clarity and unwavering reliance on very basic principles. It’s very up-lifting. Our search is for a kind of inevitability where the process leads to a naturally evolved solution. So many architects are being disruptive, often pursuing novelty to gain attention or notoriety. I am not criticizing them, but I don’t think our role, as architects, is to be disruptive. It is fine and often it is both enlightening and provocative, but that’s not what I would like to do. 

I like it when architecture exists in both dynamic tension and harmony with its context. Some buildings produce their own excitement and energy with complex and clashing forms and materials. They are very inventive, but so many of them are not designed carefully and not built well, and I wonder – How long are they going to last? Are they good investments for their client? A positive addition to their community? We don’t want that to be our legacy. And although we did not manage to create the kinds of projects that our father did – major cultural and governmental institutions all over the world – in our own, more modest way, we want our work to endure.

“We Want Our Work to Endure.” An Interview with Didi and Sandi Pei

The heirs of an architectural legacy, the Pei brothers have been forging their own path in the world with projects for some of the world’s biggest banks, cultural institutes and developers.

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