Gary Oak canteliver.

Over the years man has done some amazing feats of engineering and built some gravity defying structures. But... the lowly Gary Oak is no slouch in this department as the picture shows. I could not begin to imagine the physics, loads and stresses involved in cantilevering this huge limb out horizontally like this. I didn't have a tape with me, but it's more than 30 feet. Of course the time involved in the construction is a bit slower than most of man's creations.