This was a very simple shot, but it turned out quite interesting just the same. A decade and a half of dirt on the windows adds an element of mystery to the photo when backlit. The thing that attracted me to this scene was the array of valves in the foreground. It seemed like an odd location for them, right in front of a window like that. Looking at the resulting photo, I think the thing makes it intriguing is what you can't see -- whatever is behind that window.