Safety regulations are weird. All the exits are viewed with cameras; each door is equipped with an alarm (or even two), which notifies the police and building security in case of an alert. However, usually you don’t need any permission to get to the business center, and all the doors are open during working hours Monday to Friday, all the alarms are switched off. So, if you are interested in city views from the height without having any problems with the police, just buy a ticket to Hong Kong. — ontheroofs.com

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