World Champion Matthias Dolderer of Germany flies over the Horseshoe Bend near Lake Powell in Page, United States during the transfer flight from Indianapolis to Las Vegas to prior the final stage of the Red Bull Air Race World Championship on October 12, 2016. (Photo by Predrag Vuckovic/AFP Photo)

A line of soldiers firing handguns during a training session, circa 1920. (Photo by Keystone). P.S. All pictures are presented in high resolution.

A protester clashes with a police officer in Athens' central Syntagma (Constitution) Square in this June 15, 2011 file photo. Greece triggered the regional financial crisis in 2009 when a far higher budget deficit than previously calculated emerged. The collapse of talks with creditors in Paris last November set off a month-long sequence of events leading to elections this week and proving Greece is still the region's weak link. The vote is expected to be won by Syriza, a far-left party opposed to the bailout, worrying investors and creditors alike. (Photo by Yannis Behrakis/Reuters)

“A Little Monkey on the Cliff”. “A cold front hit the Nagano prefecture. I saw a little monkey enduring the cold in Jigokudani Monkey Park. This little monkey is really cute”. (Photo by Hidetoshi Ogata/Smithsonian Photo Contest)

Britain's Prince Harry meets Chewbacca during a visit to the Star Wars film set at Pinewood Studios near Iver Heath, west of London, Britain, April 19, 2016. Prince William and Prince Harry are touring Pinewood to visit the production workshops and meet the creative teams working behind the scenes on the Star Wars films. (Photo by Adrian Dennis/Reuters)

A policeman reacts during a clash with protestors during a protest against the proposed changes to France's working week and layoff practices, in Lyon, central France, Thursday, April 28, 2016. French protesters are back on the streets over proposed reforms to the country's labor rules and strikers have forced cancellations and delays at two airports serving Paris. (Photo by Laurent Cipriani/AP Photo)

Police in riot gear hold back demonstrators against U.S. Republican presidential candidate Donald Trump outside the Hyatt hotel where Trump is set to speak at the California GOP convention in Burlingame, California, U.S., April 29, 2016. (Photo by Noah Berger/Reuters)

A woman takes part in a global March for marijuana in Medellin, Colombia, May 7, 2016. The Global Marijuana March (GMM) is an annual rally held at different locations across the planet. It refers to cannabis-related events that occur on the first Saturday in May, or thereabouts, and may include marches, meetings, rallies, raves, concerts, festivals and information tables. (Photo by Fredy Builes/Reuters)