Would you trust a glass floor that’s an inch and a half thick when suspended 103 stories in the air? People in Chicago today can find out at the Sears Tower, which opened its new set of glass balconies for public viewing. “The Ledge,” as they’re collectively called, hangs 1,353 feet in the air. With transparent walls and ceilings, visitors say its like floating in the sky, and the view is, of course, spectacular. Don’t worry, those glass floor can withstand five tons, but just to be safe, jumping up and down is probably not a good idea.