Supreme achievements of engineering and design, corporate icons, expressions of modernity and civic pride, real-estate bonanzas, familiar and reassuring landmarks, potent symbols, testimonies to the human spirit - whether any or all of these things, skyscrapers arouse more controversy than any other building form.

Love them or hate them, one thing we cannot do is ignore them. And they suddenly seem to be getting a lot bigger and more numerous. After a century in which Chicago and New York remained unchallenged as home to the world's tallest and best known modern towers, many cities around the globe are fiercely competing for the title - nowhere more so than in Asia Pacific, where the crown has already been snatched from America by Kuala Lumpur's twin Petronas Towers, with Shanghai next in line.

If this contest were simply a matter of size and ego, the criticism often aimed at skyscrapers would be well deserved. Yet the race for the clouds obscures the more profound changes taking place in the design and construction of tall buildings involving the creation of whole new genres, and the important issues underlying those changes. Where all large towers were once designed and built more or less the same way, with standard plans and parts, many of the structures built during recent years differ radically both form each other and from anything that went before them. Some are not shaped like towers at all and, like the new genres of skyscraper, are better described more broadly as vertical architecture.

...Significantly, where skyscrapers once consumed enormous amounts of the fossil fuels that produce greenhouse gasses, they are now increasingly designed to minimise energy consumption and will in future also generate a growing share of their own power from renewable sources. Many architects and urbanists now regard tall buildings not so much as forms created in opposition to nature, as they were once perceived, but as essential elements in a sustainable or ecologically friendly strategy for urban design. In particular, they are seen as an important part of the solution to out-of-control urban growth in both the developed and developing world, where the combination of vast megacities with populations numbering tens of millions and a chronic shortage of open land is critical.

From: Sky High: Vertical Architecture. Royal Academy of Arts, 2003, p. 13.