Across from the Hilton Vienna (where I live) there is a buildings with a long concrete cantilevered roof and tree growing through it. There is a good chance the building is part of the design college complex that is in the area.
Clearly this was a design choice, and I like it. It feels good to be in a space that tips it's hat to nature--be it a mighty ol' oak or something planted after the construction. There is something about seeing a tree, that is as an obvious tare-down, be spared.
But then again, there is nothing like building around something majestic:
And then there is this...