[Christ]

I think the light is tricking you, but you could be right on that, Carlos.

I'm almost sure that it's either flat or even tilted back slightly, to evacuate water from that area, but without more perspective to the shot, I can't say for sure. I do see how the shadows are playing light tricks with making it seem the way you see it, though.

An overhead picture with the light coming from the opposite direction can make a flat space seem downhill, when it's in an odd perspective, though.