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 Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

A racegoers walks into a rubbish bin following 2016 Melbourne Cup Day at Flemington Racecourse on November 1, 2016 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images)

A racegoer is given some water as he lays on the ground following 2017 Stakes Day at Flemington Racecourse on November 11, 2017 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images)

A spectator cools herself at a water spraying fan at the Australian Open tennis championships in Melbourne, Australia, Tuesday, January 17, 2017. (Photo by Kin Cheung/AP Photo)

Two women wearing bejewelled bras kiss during the annual Sydney Gay and Lesbian Mardi Gras festival in Sydney, Australia March 4, 2017. (Photo by Jason Reed/Reuters)

Models pose backstage ahead of the Zhivago show at Mercedes-Benz Fashion Week Resort 17 Collections at Carriageworks on May 16, 2016 in Sydney, Australia. (Photo by Mark Nolan/Getty Images)