After tortured beginnings that included a false start followed by a protracted design competition during which the eventual winner "gambled" $2 million, a shroud of secrecy has enveloped the planned 1-kilometer-tall Kingdom Tower, to be sited north of Jeddah, Saudi Arabia. If built, the estimated $1.2-billion megatower would replace the 828-meter-tall Burj Khalifa as the world's tallest building. It would also owe the burj a major debt. The design team, many of whom worked on the burj, is applying lessons learned in Dubai to the Kingdom Tower in a concerted effort to simplify design and construction of the concrete structure.

Currently, there is no mention of the Kingdom Tower—the pet project of a Saudi prince named Alwaleed Bin Talal Bin Abdulaziz—among the projects listed on the website of the skyscraper's general contractor and part owner, the Saudi Binladin Group. SBG is mute on the subject. The developer, Kingdom Holding Co.'s Jeddah Economic Co., has muzzled the entire design team. The Council on Tall Buildings & Urban Habitat lists the building as proposed, though pile construction was scheduled to begin last month. Reports that the work has begun could not be confirmed, but sources familiar with the situation, who requested anonymity, do confirm that design development continues.

Last summer, the developer unveiled a scheme for a 5.3-sq-km mini-city called Kingdom City, which would cost $20 billion and include the Kingdom Tower. The sleek, tapered tower—designed by Chicago-based Adrian Smith + Gordon Gill Architecture (AS+GG), with the Chicago office of structural engineer Thornton Tomasetti (TT) and mechanical engineer Environmental Systems Design Inc., also of Chicago—would enclose 530,000 sq meters. 

AS+GG was formed in 2006, after Smith and Gill left the Chicago office of Skidmore Owings & Merrill. While at SOM, Smith was the lead designer for the Burj Khalifa. Many from the burj team currently work at AS+GG, including Peter A. Weismantle, AS+GG's director of supertall building technology. Robert C. Sinn, currently a TT principal, also worked on the burj while at SOM. And both buildings have the same wind engineer, Guelph, Ontario, Canada-based Rowan Williams Davies & Irwin Inc. (RWDI) and the same elevator consultant, Galveston, Texas-based James A. Fortune.

In retrospect, one could almost consider the Burj Khalifa as a living laboratory for supertower design. During interviews last fall (before the project went quiet), members of the Kingdom Tower design team talked about lessons they learned from the burj, mostly pertaining to the megatower's shape, structure and skin.

The Kingdom Tower's design may be simpler to build, but the project's beginnings were much more complicated than the burj's. For the burj, the developer held a three-week ideas competition, suggested by Smith, to narrow the field from the several architects interviewed. The deal with SOM was soon sealed on a handshake. After the selection, conceptual design matured over one and a half years.

The building now known as the Kingdom Tower was initially called the Mile High Tower. Eventually, the developer abandoned as impractical the idea for a tower a mile tall. After that followed a strung-out design competition, which lasted nine months instead of two, for a shorter building. During the competition phase, representatives of AS+GG made eight trips to Saudi Arabia to present schemes. The firm even built and shipped 10-ft-tall models. "It was really expensive," Smith said. The competition "wasn't for the faint of heart."

The selection was supposed to be made by September 2009. By that time, however, five of the eight initial submissions still had to present to the prince. By December, two teams were left: AS+GG and SOM. Ultimately, AS+GG was selected in February 2010.

Smith calls the selection process "torturous," for both his firm and SOM. "I knew it was a big gamble, but it was something we wanted badly," he said. "Had we not won, we would have lost $2 million and would have had to lay off 30 to 40 people because we were all holding staff for this project," he said.

The team wasn't out of the woods yet. In December 2010, well into design development, the project went on hold for six months. "The owner didn't have its own structure together yet," said Smith.