The Chanin building is a rather obscure old school new york skyscraper that is near to the Chrysler building.
If humans have disappeared, how long can it last without humans around?
2 days: The power goes off.
100 years: The concrete structure gives this building an edge over more modern buildings. While the building is pretty much a garden, the overall building outline remains.
200 years: Remember the Chrysler building? Well, this is around the time when the tower fell and took out the shell of the Chanin building, destroying the rest of the building in process.
Without the Chrysler building, it most likely would've lasted another hundred years, but eventually the concrete will wear out and the shell will crumble like a cookie.