The cube-shaped Mukaab will be the cenerpiece of Riyadh's new downtown (Credit NMDC)

The seven monarchies of the United Arab Emirates (UAE) are known for their mega projects. Dubai, the UAE's largest and most populous emirate, is home to the world's tallest building, biggest mall, and largest man-made island. Now, Saudi Arabia has announced plans to build the "World's Largest Inner City Building" in the capital city of Riyadh.