How tall could we really build? After a century of competition, skyscrapers are reaching new extremes: Saudi Arabia’s upcoming 1-kilometer-tall Kingdom Tower in Jeddah is set to triple the Empire State Building’s height. In this episode of “The Limit,” we climbed inside the hidden parts of the world’s tallest towers and talked to the people who built them to ask: What would it take to build a mile-high tower? Who would pay for it? And why do we keep reaching higher?