10 years after people: due to power long gone the window buckets have not washed the Burj Khalifa's façade in a decade leaving the exterior of the building looking dirty from collecting wind-blown sand. Due to corrosion, one of the Burj Khalifa's window-washing buckets falls from the building.
250 years after people: Over two centuries of corrosion and sandstorms have shredded the Burj Khalifa's exterior. The columns of the building's bottom have corroded more than its top due to closer proximty to saltwater. Finally a sandstorm blows in, the building's bottom columns fail and the Burj Khalifa collapses.