Carolina Gutierrez (center L), 17, and Neuil Valdez, 18, use mobile phones to connect to the internet at a hotspot in downtown Havana, Cuba, December 12, 2016. (Photo by Alexandre Meneghini/Reuters)

A Russian prisoner eating bread. (Photo by Hulton Archive/Getty Images). Finland, circa 1940

Members of an American landing party assist troops whose landing craft was sunk by enemy fire off Omaha beach, near Colleville sur Mer, France, June 6, 1944. REUTERS/Weintraub/US National Archives

A man standing on the first cables during the construction of the Golden Gate Bridge with the Presidio and San Francisco in the background, San Francisco, California, 1935. (Photo by Underwood Archives/Getty Images)

Rock and roll musician Elvis Presley during a press conference after his first performance at the International Hotel in Las vegas, Nevada on August 1, 1969. (Photo by Michael Ochs Archives/Getty Images)

A staff member sets up a ROBOTLEO robot at the Global Mobile Internet Conference (GMIC) 2017 in Beijing, China April 28, 2017. (Photo by Jason Lee/Reuters)

Dancers at the Windmill Theatre in London, England practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)

A German rifleman beside the corpse of a French soldier in a trench at Fort Vaux, France, 1916. (Photo by Hulton Archive/Getty Images)