I have had a closer look and it may in fact be 2 floors, I have used the top picture you posted Locutusofbored and I have added highlights to show the floors (amateurish using paint I know).
Nope. The corridors are not the same height as the windows. In fact, if you look through the windows, you can see only one of the three rows of "rectangle" patterns on the walls. Your red arrow is also pointing at what I assume you think is a floor, but it isn't.