Strong horizontals in foreground, mid and upper third and the dominant verticals of the columns all create a great context for the human sized verticals at the heart of the image. Timing for sure but also the artists eyes to *see* beyond the simplicity.
The image would, I believe, work without the manipulation, which makes it look a little false, although it has a lot of impact. The strength of the structure, the pillars and other components, works well in B&W, especially with the vignette. Nice work.
Of course it's difficult to say this without seeing the original, but personally I thought the black and white treatment worked well here. Love some of the textures and patterns in the background.