Hope you're not afraid of heights. Experts say the number of "megatalls"—skyscrapers over 600 meters—is going to more than double in the next five years.

There are currently three megatalls in the world— the first was Burj Khalifa in Dubai, which holds the title of world's tallest building. The Council on Tall Buildings and Urban Habitat (CTBUH) says that four more megatalls are currently planned, which would bring the total to seven. Amongst them are the Kingdom Tower (above), a staggering 1,000 meters tall planned for Jeddah, Saudi Arabia.