When I did my traveling through Asian countries I was often struck with a kind of wonder and awe by palaces and pleasure domes sitting abandoned, decaying, garbage filled. What happened? How/why did those magnificent buildings die? Even abandoned and decaying, they seemed magnificent. Why were people living in squalor nearby such former magnificence?
I think that first the souls of leaders become ill and degenerate, then society sickens, and the buildings die.