Experts say there is no easy path to truly sustainable skyscrapers"/> If done in 2015 as expected, Shanghai Tower (center), on its way to 632 m, would rank as the world's second-tallest skyscraper.

These are the tallest buildings ever constructed—starting with the single tallest one in the world. ... “One easy way physically to do that, ... blocky office building’s design is unusual, ...

Proposed building would be more than 1,100 feet tall. ... which is currently the world’s tallest wooden building. Drawings of the new tower ... "Timber buildings are very easy to associate ...