The Great Spadoni
"The Great Spadoni," aka Paul Krause from Germany, was one of the great masters of lifting, balancing and juggling heavy weights, a discipline known as jongleurs de force.
One of his best known feats is pictured at the right:
To begin, he was driven upon the stage in a full-sized dog cart. He then dismounted, removed the wheels -- which were then set spinning on pivots fixed to the points of the shafts --- lifted the dog cart in his arms and finally balanced it on his chin.
While the balance aspect is certainly impressive (to say the least!), the amount of whole-body strength involved in getting the cart into position in the first place and the level of neck strength necessary to keep it aloft, may be even more so.