Old Heidelberg, Dog with Pipe, 1905. (Photo by Detroit Publishing Company)

In this Wednesday, March 18, 2015 photo, limestone quarry workers walk through a cloud of dust spewed into the air by rotor blades of the stone-cutting machinery in the desert of Minya, southern Egypt. Around 45,000 people, including children, work in an estimated 1,500 quarries, digging out stones that later will be used in construction or powdered to be used by pharmaceutical and ceramic companies. (Photo by Mosa'ab Elshamy/AP Photo)

Mohamed Mostafa, 35, carries dyed yarns at a dye workshop in old Cairo, Egypt, March 17, 2016. Egypt's hard currency crisis and competition from modern factories in Asia and at home threaten one of the last dye workshops in Egypt. But one of its owners takes comfort in the trade's ancient resilience. Mohamed Mostafa boasts that the profession dates back 3,000 years, so it can survive anything. (Photo by Amr Abdallah Dalsh/Reuters)

An Egyptian university student drives a hybrid racing car he built with his team to compete at the Global Hybrid-Electric Challenge in Cairo, Egypt September 2, 2016. (Photo by Mohamed Abd El Ghany/Reuters)

In this Wednesday, July 13, 2016, handout image provided by Solar Impulse, the Solar Impulse 2 flying over the pyramids, Egypt Cairo. The experimental solar-powered airplane has arrived in Egypt as part of its global voyage. (Photo by Jean Revillard, Rezo via the AP Photo)

Young demonstrators (many shirtless) shout and cheer as they overturn a truck trailer in the Reflecting Pool on the Mall facing the Washington Monument during the “Honor America Day Smoke-In” thrown by marijuana activists to protest the official “Honor America Day” ceremonies being held at the Lincoln Memorial, Washington, DC, July 4, 1970. (Photo by David Fenton/Getty Images)

Josef Stalin's head is left in a Budapest street after a statue to the communist dictator was torn from its plinth during the Hungarian Revolution in 1956. (Photo by Robert Hofbauer/Radio Free Europe/Radio Liberty)

Women's International Football, England team train for England v France match. Picture shows young footballer Jeannie Allott. Jeannie Alott was England youngest ever female goal scorer. At the age of sixteen years, and one day, she scored in the first official England v Scotland match in Greenock, Scotland on the 18th November 1972. Scotland (2) – England (3) Picture taken 6th November 1974. (Photo by Monte Fresco/Mirrorpix)