At nearly 2,717 feet, Dubai’s Burj Khalifa is the world’s tallest building. Its record-breaking height is inarguable, but the category of building? That’s so last century. Burj Khalifa isn’t just a building -- it’s a vertical city, holding nearly 10,000 people. If you’re feeling brave, board an elevator sporting an interactive history of the city and go straight to the top, where an observation deck -- and the Dubai city skyline -- await.