Yes, obviously, but how is it possible for the building to withstand the weight of the dirt, grass and trees?

With columns: http://en.wikipedia.org/wiki/Column

Interesting technology, this Column. Thanks for sharing!

If you design for 100 story buildings, you can design for a few story building with dirt on top.

It's fixing the leaks in 20 years that's the problem. But I guess the building just has to outlast the company...

Nah, we've gotten pretty good at sealing concrete. You put enough tar and landscaping fabric under there, it'll last a while.

Grass and trees don't weigh a lot, compared to dirt, or earth, or water-laden earth. Compare a moderate snowfall of a couple of feet with a foot of dirt and some rainfall.

But these should be zoned, yes.