Today is Skyscraper Day.
From the Chrysler Building to the Burj Khalifa in Dubai, engineers and architects continue to reach for the stars.
Steel along with elevators are key ingredients. Afterall, who would (or even could) climb all those stairs. And the windows! It takes 3 months to clean all of the 24,000 windows of the Burj Khalifa in Dubai, the worlds tallest (at 2,722') skyscraper. Once they are done, they start all over again.
Watch a video of how it's done here.
Striking photos of the world's skyscrapers can be seen here, each with a pull-down menu of fact and figures.
Caution, just watching or looking may cause vertigo!