Degenerate
Even if you have a building, it will eventually turn back into dirt. Everything will degenerate eventually. A brick falls off here, a door comes loose there. Nothing can last forever.
だ
お, くず
None
As you watch the building degenerate, you can't help but think of your dad (だ). You had to watch him waste away the same way of a degenerative disease. Why do people have to die, dad?