Soviet Army soldiers sit on their tanks in front of the Czechoslovak Radio station building in central Prague during the first day of Soviet-led invasion to then Czechoslovakia on August 21, 1968. (Photo by Libor Hajsky/Reuters)

In a July 14, 1967 file photo, left, National Guardsmen make their way along Market Street in Newark, N.J, after an evening of deadly rioting and looting in what came to be known as the Newark riots. In a June 16, 2017 photo, right, an ambulance drives on the same block 50 years later. (Photo by AP Photo/File, left; Julio Cortez, right)

A runner in fancy dress participates in the Virgin London Marathon 2013 on April 21, 2013 in London, England. (Photo by Tom Dulat/Getty Images)

Pantless people stand on a subway platform on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a “celebration of silliness” is designed to make fellow subway riders laugh and smile. (Photo by Timothy A. Clary/AFP Photo)

Actress Rosie Huntington-Whiteley arrives at the LACMA Art + Gala at LACMA on October 27, 2012 in Los Angeles, California. (Photo by Jon Kopaloff/FilmMagic)

Bob Woodward looks at the reconstruction he built of the Orpheus Pavement at Prinknash Abbey on March 31, 2010 in Gloucester, England. The replica mosiac, made of more than one-and-a-half million pieces of stone is described as one of the most significant archaeological projects of recent times. (Photo by Matt Cardy/Getty Images)

Sunrise over Maridalsvannet in the forest areas near the outskirts of Oslo, the capital of Norway. Winter is approaching, the first snow covers the ground, and the water has already got a thin layer of ice. The temperature is significantly below the freezing point, the air is clear and the sun colors the morning clouds in deep tones. (Photo by Tore-Thiis-Fjeld/Getty Images)

Series of portraits by Muir Vidler for his project Rebels Without a Pause: Britain's ageing rebels and mavericks.