If you look carefuly at the picture (right down corner) you can see that this isn't an arch that you can see through, but it's an arch-shaped window and all you see inside it's the reflexion of what was going on behind me.
Thanks to those who saw the reflexion in my picture and gaved constructive comments.
like the idea, with the window arch serving as an underpass comceptually for your photo. the picture seems to be a bit over-brightened, imo, when i look at the source greenery and brick arch.
Very nice natural framing. It is hard at first to tell it is a reflection, but it is, so meets challenge fine. I agree with your title... It gives a "throught the looking glass" feel.