This image showed up on a pawn stars episode. My dad thought it was real, and was extremely curious as to the story behind it. I, on the other hand, think it's fake. It looks like the set to a movie rather than a real event. Note the men dressed in rennaissance-era armor. While that seems like good evidence that it's fake, it could be ceremonial, like in the vatican (this image was brought up while they were talking about Giovanni Bruno).
It is from a movie, as far as I can find out the copyright is currently held by the Everett Collection, who specialize in movie stills and other movie images. Unfortunately I wasn't able to find the name of the actual movie it came from.
For a real burning, depending on where you were you might be surrounded by the pyre or completely covered by it, or dropped directly onto the pyre once it was well lit. The victim (or rather, stuntman or dummy) in the photo is ridiculously far above the pyre, and also that's an unreasonably complicated wooden platform to build around something that's about to be burnt. The weapons carried by the soldiers would also indicate that the supposed period is one where cameras would not exist to be able to take such a clear photo. And in the middle right of the picture, you can just make out (it's clearer in better quality images) an electric cable or antenna wire hanging between two windows. So yeah, that's not real.