This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

People in historical uniforms prepare for a parade at Red Square commemorating the 75th anniversary of the Red Army’s defence of Moscow during the second world war in Moscow, Russia on November 7, 2016. (Photo by Stanislav Krasilnikov/TASS)

The Eastern City Gate apartment buildings complex stands in the Konjarnik neighbourhood in Belgrade, Serbia, July 30, 2019. Brutalism, an architectural style popular in the 1950s and 1960s, based on crude, block-like forms cast from concrete was popular throughout the eastern bloc. (Photo by Marko Djurica/Reuters)

Dafna Ben Nun with the Emperor penguins. Heres the brilliant picture of a cheeky baby penguin playfully winking at a photographer. The adorable snap was taken while a group of mischievous chicks were playing with their parents. (Photo by Dafna Ben Nun/Caters News)

Alphajet aircraft draw a heart-shaped message in the sky during the 2010 presentation show of the French aerobatics team Patrouille de France, over the French city of Salon-de-Provence. (Photo by Gerard Julien/AFP Photo)

Terashima Takeshi and Akaishi Kazuya of Japan block a shot from Indonesia during day one of the ISTAF Super Series at Palembang Sport Convention Center on February 23, 2012 in Palembang, Sumatra, Indonesia. (Photo by Nicky Loh/Getty Images for UFA Sports)

Enthusiasts gathered at Cad East in Snowdonia National Park, England to take pictures of F-15 Eagle fighters as they completed the Mach Loop, November 2017. (Photo by Caters News Agency)

A hippopotamus performs during a show at the circus in Krasnoyarsk, Siberia, Russia, July 7, 2016. (Photo by Ilya Naymushin/Reuters)