Given the length and cross section (looks like 3/4" or larger compared to that tape measure) of that bar, and the nice even twist all along the length, I would say that bar was machine twisted.
Probably a length of old lightning rod grounding rod. Some of the old barns around here still have the lightning rods intact, and a lot of them have long lengths of bar such as this that go from the peak to the ground. I don't know why they used twisted, other than for looks, probably.
I used to live beside one such barn, it had an intricate system that tied all the lightning rod "points" together, with an elevated "runner" across the peak on brackets. I assume that was so they only had to use one drop to the ground.