Great leading line here, and perspective, plus wonderful texturess, in this very simple image.....
I also like the color tones that help to balance this image.....
Karen, I like this image. I like the textures and the large blocks it forms. I think the selective desat works very nicely in an almost abstract way. Now that the challenge is over, I think you could have some fun with it by cropping the top down to eliminate all the sky (square aspect ratio) and then putting a gradient map adjustment layer on it. Try all sorts of combinations of colors in the gradient. I think you'll get some really cool abstract images.
Karen, it is a striking wall, but this treatment leads me to wonder why only one part of it is in color. Might it might be better to have both parts in color?