>>2688674 (lb)
>>The Paul VI audience hall is merely looking like a snake head due to the wide-angle lens photography.
wide-angle lenses are uniform out from the center of confusion, meaning the ground would bow as well. So no to that. Otherwise you got shitty glass.
Also, this photo you use demonstrates it's not merely a matter of perspective or a wide-angle lens effect. Note, the balcony railing has a slight but very noticeable curvature to it. This curvature is opposite the arc of the ceiling lines. This demonstrates the lens effect discussed earlier, independent of the forced perspective caused by the ceiling lines that lead to the snake mouth opening.
In short, it was designed to look exactly how it looks, like a snake mouth.