The hymenocallis flower may have inspired the design team at Chicago’s Skidmore, Owings & Merrill, but the Burj Khalifa has an aggressive look, seeming to pierce the sky like a crystal weapon. The tower’s flashiest occupants are the 160-room Armani Hotel and an extra 144 Armani Residences. It may not cling to its status as world’s tallest building for long; Mecca’s Kingdom Tower is scheduled to complete construction in 2016. (iStockphoto)