The Sacred Flame by Selma Lagerlof

A great many years ago, when the city of Florence had only just been made a republic, a man lived there named Raniero di Raniero. He was the son of an armorer, and had learned his father's trade, but he did not care much to pursue it.

This Raniero was the strongest of men. It was said of him that he bore a heavy iron armor as lightly as others wear a silk shirt. He was still a young man, but already he had given many proofs of his strength. Once he was in a house where grain was stored in the loft. Too much grain had been heaped there; and while Raniero was in the house one of the loft beams broke down, and the whole roof was about to fall in. He raised his arms and held the roof up until the people managed to fetch beams and poles to prop it.