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

Pitch invader Kinsey Wolanski is taken away by security during the Champions League final soccer match between Tottenham Hotspur and Liverpool at the Wanda Metropolitano Stadium in Madrid, Saturday, June 1, 2019. (Photo by Toby Melville/Reuters)

A demonstrator attends a protest against fare hikes for city buses in Rio de Janeiro January 16, 2015. Amid a marked economic downturn and high inflation, bus fares went up in Sao Paulo, Brazil's largest city, from 3 to 3.50 reais, and in Rio, the former capital, from 3.0 to 3.40 reais. (Photo by Mauro Pimentel/Reuters)

American students going wild during their Spring Break week-long recess in Cancun, Mexico on March 10, 2007. (Photo by Keystone USA/ZUMA Press/Rex Features/Shutterstock)

A visitor wears an outfit as she watches the St. George NextGen show for Fashion Week in Sydney on May 16, 2017. (Photo by Peter Parks/AFP Photo)

In this February 14, 2019 photo, a newlywed couple kisses while posing for photos at one of several free sets placed for newlyweds to take cell phone photos of themselves following a mass wedding ceremony on Valentine's Day in Mexico City. Hundreds of couples of all ages, many with their children, gathered to legally tie the knot in a mass ceremony in the capital's Venustiano Carranza neighborhood. (Photo by Rebecca Blackwell/AP Photo)

A partially burned American flag lies on the street near the spot where Michael Brown was killed before an event to mark the one year anniversary of his killing in Ferguson, Missouri August 9, 2015. (Photo by Rick Wilking/Reuters)

Haitian policemen arrest a demonstrator with machetes at the end of a march, in Port-au-Prince, on November 26, 2015. Supporters of Fanmi Lavalas and Petit Dessalines political parties marched to protest against the results given by the Provisional Electoral Council (CEP), against the Haitian President Michel Martelly, and against the candidate of the ruling party Jovenel Moise. Provisional Electoral Council (CEP) confirmed this week that Haiti's presidential election will go to a runoff on December 27, between ruling party candidate Jovenel Moise and Jude Celestin, close to former president Rene Preval. (Photo by Hector Retamal/AFP Photo)