What about growing your skyscraper?

From Der Spiegel:

Three young German architects are designing structures made completely out of living trees, including a pavilion for concerts in downtown Stuttgart. But designing the ultimate treehouse turns out to be trickier than one might expect.

How?

The basis of their work is always the same. First, the architects build a conventional support structure. Young, flexible trees are attached to the structure and bent into the desired shape. As the trees grow, they take on more and more of a load-bearing function. After a few years — and what Ludwig calls a “botanical certificate of fitness” inspection by a structural engineer — the support structure can be removed. At which point the roof and floors that have been inserted should be supported entirely by the trees