My old battered shoes climbed the worlds tallest building today. What an amazing structure! Tweeting from 820 meters straight up! — joemcnallyphoto, via instagram.com

Despite the reassuring rivets in the 1,500-pound glass panels, the calm stillness of the air at the Windy City’s pinnacle and the security of a 10,000-pound weight capacity for each of the four 4.3-foot-deep glass boxes that protrude past the sheer edge of the Western Hemisphere’s tallest building — despite all that, you still feel twinges of queasiness. — nytimes.com