It's hard work cleaning the windows of the world's tallest building, but somebody has to do it.
The Burj Khalifa in Dubai is covered in 24,000 panes of glass.
The workers who clean them start at the 160th floor and work their way down. That's more than 2,700 feet.
Before they start their work, they check and double-check their harnesses and ropes. They also measure wind speed because a gust of wind could be dangerous.
It takes three months to clean every window, and then crews start all over again.
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