The race to build world's tallest building

As city skylines around the globe fill with towering buildings, there is a drive to reach heights never reached before.

It's amazing to think that back in 1900, the world's tallest building was a relatively humble city hall in Philadelphia. How times have changed!

As Saudi Arabia's 1-km-high Kingdom Tower begins construction, here's a look back at the how the aspirations of architects (and the advance of modern technology) has sent our buildings skyward.

Simply click on the infographic below to enlarge.