The 162-meter (531-foot) British Airways i360, which opens to the public on August 4, is the world's tallest moving observation tower and also its Guinness record breaking slimmest thanks to a diameter of 3.9 meters (12.8 feet) and a height-to-width ratio of over 40:1. After airport-style security checks, visitors enter the futuristic glass-and-steel pod and slow glide to a height of 138 meters (453 feet), an experience akin to floating in the air given the 360-degree views out as you walk aroun