An Aden civilian crouching in terror as British soldiers threaten him during Arabian demonstrations in Crater. (Photo by Express Newspapers/Getty Images). 1967

A worker pauses for a sandwich, resting on a girder during the construction of a skycraper. (Photo by Hulton Archive/Getty Images). Circa 1930

Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

A dejected German Grenadier carrying a machine gun on his shoulder in front of a building on fire during the German retreat in Russia. (Photo by Keystone/Getty Images). 1944

“John Thomson (14 June 1837 – 29 September 1921) was a pioneering Scottish photographer, geographer and traveller. He was one of the first photographers to travel to the Far East, documenting the people, landscapes and artifacts of eastern cultures. Upon returning home, his work among the street people of London cemented his reputation, and is regarded as a classic instance of social documentary which laid the foundations for photojournalism. He went on to become a portrait photographer of High Society in Mayfair, gaining the Royal Warrant in 1881”. – Wikipedia. Photo: Ex Omnibus Driver. (Photo by John Thomson/LSE Digital Library)

A Hindu Sadhu smokes marijuana from a chillum inside the Pashupatinath Temple premise in Kathmandu, Nepal on March 6, 2016. Holy men from India and Nepal come to celebrate the festival of Maha Shivaratri by smoking, smearing their bodies with ash, offering prayers devoted to the Hindu Deity, Lord Shiva. (Photo by Skanda Gautam via ZUMA Wire)

Young U.S. visitors pose for a photograph next to a vintage car in Havana March 16, 2016. (Photo by Ueslei Marcelino/Reuters)