I like the shot and the composition, but to be finicky, I'd say that perhaps the foreground should have a little gaussian blur to lead the eye into the picture - it's a tad flat as it is? Also, I don't know whether it's a sharpening, or compression artifact, but there's a fringe effect on the underside of the arch, which could benefit from minimisation?
Goodness me, look at me carrying on like it's posted in critique! Good shot and good eye - I do really like the composition. For me, the B&W version works more effectively as there's a lot of texture in the scene.
I love the frame-inside-a-frame. It really sets the mood here nicely, too. I think that if it were my shot, I would up the contrast a bit, but that may just be me - it looks great as it is, too! I'm really partial to the B&W (of course, I'm partial to B&Ws in general!); overall very nice shot!