You being in the heart of America's oil and oil refining area, should notice that in the photo's above at the beginning of this post, one plaque shows the finished oil refinery; therefore, I do not believe the "background" refinery was removed.
In any case, this is most wonderful and excellent work by our colleague in Bulgaria.
Highveldt
I didn't see "The" refinery as I was fascinated with the background removal in and surrounding the lettering.
There are a thousand ways to remove this background.
Right now, I am asking Anmarinov how "He" removed it.
If it had been a buckle, I would have known the letters had been soldered on. This was relief work.