The forces of nature....
The forces of nature are capable of breaking down mountains, so we must assume that a building will also not last indefinitely.
Subsidence, settlement, heave, sway, bouncy floors, bulging walls, cracks, expansion and contraction are all forms of structural movement. Such movement occurs all the time, and usually its magnitude is so small it passes unnoticed. Only when distortions and cracks threaten the use or safety of the structure need we be concerned.
Image by Millie Cattlin, taken along Highline, New York, 2014