The Council on Tall Buildings and Urban Habitat said that it is possible to build a tower that can stretch up to 1.24 miles high. But building at such a height could impose many structural challenges, says Dr. Sang Dae Kim, the council's chairman. "There might be constraints for the structural engineering -- we don't know many things," Kim said. "When you go up to one of two kilometers, we don't have much information surrounding the wind conditions."
With the announcement by Saudi Prince al-Walid bin Talal that he intends to build a tower approximately 5,000 feet tall outside the city of Jeddah, Saudi Arabia, engineers and architects are once again asking how high skyscrapers can go. Design features such as a "buttressed core" or a giant pendulum can help correct the sway caused by high-altitude winds, and mass dampers can counteract the shock of an earthquake. "Structural engineering-wise, it's not even difficult," says one expert of the mile-high tower, which will be about twice the height of the current record-holder, the Burj Dubai, which is still under construction.