Mary Pickford takes a picture of husband Douglas Fairbanks, Sr., who is executing a handstand on the roof of a building on December 19, 1920. (Photo by Bettmann Archive/Getty Images)

A woman plays around as she walks across a glass-bottomed suspension bridge in a scenic zone in Pingjiang county in southern China's Hunan province Thursday, September 24, 2015. The bridge, 300 meters (984 feet) long and 180 meters (590 feet), opened to visitors on Thursday for the first time since its conversion from a regular suspension bridge was completed. (Photo by Chinatopix Via AP Photo)