Aric Chen:  The Bank of China Tower was commissioned in the early- to mid-1980s, when negotiations were underway for Britain’s return of Hong Kong to China. Could you say a few words about how the building arose from this context, and how you and your father got involved?

Sandi Pei:  If you recall, at the time, the HSBC building [designed by Norman Foster] was under construction. It was a real challenge to come forward with a building design that could rival this impressive structure at a fraction of the cost. In addition, the impending transfer of Hong Kong’s governance from British rule brought daily focus on China’s repossession of the colony and gave heightened symbolism to this prominent tower announced during a period of tense negotiations. At the same time, the charged atmosphere added to the consequential nature of the commission and intensified every decision that we made in our development of the project.

The project came soon after the Fragrant Hill Hotel was completed [in Beijing]. In fact, the first meeting my father had with the bank was scheduled in Hong Kong immediately following the opening dedication in October 1982. My father knew about this invitation ahead of time, so by the time he had this meeting, he had already consulted with his father, who had consented to him taking on this commission.

Chen: Because your grandfather, Pei Tsu-Yee, was at one point the General Manager of the Bank of China, in the 1940s.

Pei: Exactly. My father was not going to entertain this kind of project without his consent. My grandfather, however, supported his son taking on the project. It was obviously a very important commission and unquestionably a huge honour.

Chen: So what were some of the architectural challenges posed by the project?

Pei: The building site was along the edge of Central and had many shortcomings, among them poor accessibility and reduced visibility from the harbour. But its chief advantage came from its location, which fell immediately outside of the flight path to Kai Tak Airport, and that permitted a tall tower to be constructed. With that knowledge, the challenge was to create a tall building that could be built to withstand wind forces approximately twice that for New York and three times that for Los Angeles, and within a fixed budget set in Beijing! Therefore, any solution would have to prove economically viable as well as structurally sound, to say nothing of the challenge of creating a distinctive design that might stand up against Foster’s innovative building then under construction barely 100 metres away.

Chen: How did you and your father develop the form of the building?

Pei: I can’t remember the exact date, but it certainly occurred in the weeks immediately following our return, as the earliest discussion was at our country house [in Katonah, New York]. My father and I sat down with a site plan and after analysing its constraints and opportunities he drew a square that he divided diagonally into four quadrants and, rather matter-of-factly, suggested that I construct four sticks of this shape with tapered tops. It was that simple!

The construction of these four independent shafts allowed us to manipulate the form easily by sliding them up and down to create a progression of square packages, each concluding with tapered tops tilted toward the center.

Chen: Where do you think that idea came from?

Pei: I don’t know. But it was not uncommon for my father to begin discussions with his core team only after he had a specific idea that he wanted to test, even if it was only vaguely imagined. He accepted the responsibility to lead the effort and not to squander valuable time. The diagram that he drew looked simple but conveyed authority and conviction. In any event, once the diagram took shape and appeared promising, lines were drawn to form the primary diagonal structure, creating a web that knitted the quadrants together. It was this model that was first shown to Les Robertson, the trusted and brilliant engineer whom my father habitually engaged for his projects.

Chen: And the rest is history.

Pei: Exactly. It was immediately apparent there was something quite exciting going on. When Les looked at the model he immediately intuited that it was a realistic approach to the challenges posed by the height and wind forces. Subsequent tests proved even more promising, as the composite structure reduced steel tonnage by 40% for buildings of comparable height and the resulting cost savings kept us within budget.

Chen: The result is of course one of the icons of the Hong Kong skyline, but one thing that people don’t often think about with the building is the abstracted Chinese garden at the base. Could you tell us a little bit about that?

Pei: The original site did not consist of the boundaries that were finally agreed to. There was a public open space on one corner that we exchanged with the government, so that we could configure the building to sit parallel to Central. We felt that unless the building was oriented to the predominant grid of the downtown, it would look very awkward.

The site’s reorientation created two large, roughly equivalent, sloping triangular patches that we eventually formed into cascading water gardens. We separated them from the roads with steps and two high granite walls that contained the gardens and buffered the site from the traffic and which also became the exhaust and exit routes from the garage. So there were both urbanistic and internal planning issues that we addressed from the very beginning that were important to the success of the project.

Chen: Thirty years on, how do you think the building is received now compared to when it was completed?

Pei: Well, I think the building has become entirely accepted by the public. And it is a local landmark. I think, thanks to the bank, that the building continues to be something that people value, and they are proud that it was designed by my father. Despite all of the other buildings that have come since then, which are much taller and in many ways more prominent, I think the Bank of China tower remains one of the most recognisable and iconic buildings in Hong Kong.

Chen: You say so yourself, but I think others would agree.

Pei: It’s one of the best buildings in Hong Kong, I do believe that. And I believe most people would say it’s one of the five most prominent buildings, right? So I’m very happy about that.