Thank you, all.
I think it is an old threshing machine. I took the shot on a recent holiday Ireland at a show farm (ah, the wonders of a 7-year-old daughter!). I've attached another shot of it below.
I nearly always hit "v" (John) to see how a photo would look in black and white. I didn't try with this one because I felt that the colours were important, but I've given it a go. It looks OK to me, but I don't like it as much as the colour version. What do you think?
I've fiddled a bit with the original, increasing the contrast and lowering the vibrancy a tad (Jennifer) and burning in the upper-right bolt a little (Slobodan and Eric). I think those suggestions have improved it; I've also raised the "shadows" slider to bring out a little more detail of the inside.