2 days after people: New York City goes dark. The Freedom Tower loses power and fades into the night.
5 years after people: The first windows are breaking in the building. They let in water and animals.
20 years after people: Plants are growing in the building. Water from the Hudson River has infiltrated the basement levels of the building.
100 years after people: The spire on top of the building falls off and crashes into the plaza below.
300 years after people: After 300 years of erosion and lack of maintenance since humans disappeared, the building finally falls from the skyline.