The Mountain from 'Game of Thrones' literally went medieval on a ridiculously huge log

We already knew that Hafthor Julius Bjornsson, a.k.a. Gregor "The Mountain" Clegane on "Game of Thrones," is strong -- I mean, just look at him. But he's out to show the world that he's the strongest, and he is willing to take on 1,000-year old challenges to prove his point.