Skyscrapers have been around since the so-called “Chicago-style” architecture arose in the 1880’s. Developers routinely seek to push the envelope on height in order to gain more rentable space, and make the structure economically viable. Bloomberg reports today that a mile-high skyscraper may be possible by 2025. Exactly what are we proving to ourselves by designing and building structures this tall? Is there a height limit on cost-effectiveness?

The consensus is that any building over one kilometer tall will require two or three buildings at the base, with connections between or among them at higher elevations in order to provide stability and bracing. To put this height in perspective, the Burj Khalifa in Dubai, the current tallest building, is 818 meters; it will be eclipsed by the Kingdom Tower, in Jeddah, which reportedly will reach one kilometer when completed in 2018 (original plans to build it to the height of one mile were abandoned).

Tall buildings require sophisticated methods of getting people up and down. Sophisticated methods of transport cost money. The more robust bracing and structural systems required for such buildings also cost money. (At a mere 452 meters, the Petronas Towers in Malaysia provide an example of bracing.) Not to mention mechanical systems at multiple levels. And how do you suppose one gets adequate water pressure to flush the toilets next to the observation deck one mile up? At some point the cost of infrastructure deflects the cost-benefit curve downward. This is not about cost-effective projects.

Of course, the firms involved in such tall buildings will enjoy a certain cachet, having their names associated with the world’s highest structures. The opportunity to design or build such a structure may be incalculable. But someone has to bankroll it. As quoted in the Bloomberg article, Timothy Johnson, Chair of the Council on Tall Buildings and Urban Habitat, said: “But you kind of ask yourself, ‘why would anyone want to [build] that high?’ And some of it is just human ego.” Bingo!