Top 10 tallest structures

Don't look down! 125 years after French engineer Gustave Eiffel designed his eponymous tower, tourists still flock to Paris to climb it. Here's a look at our 10 favorite tall structures from around the world.

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  Highest clock: Abraj Al-Bait

  The third tallest building and world's highest clock tower is the Abraj Al-Bait Tower in Mecca, Saudi Arabia. Overlooking Masjid al Haram, the world's largest mosque and Islam's most sacred site, the 601-meter building was completed in 2012 and houses a prayer room, a hotel and a 20-storey shopping mall.