A sign is posted in front of the new Yoga Room at San Francisco International Airport's terminal two on January 26, 2012 in San Francisco, California. (Photo by Justin Sullivan/Getty Images)

“For most Londoners, the most common view they enjoy as they trudge to work is the back of another commuter's head. But now, thanks to the Streetmuseum app, anyone traipsing through the capital's streets can step back in time to see what London looked like in the 19th and 20th century compared with today – all in the same image”. – Joe Krishnan via The Independent. Photo: A street scene in London’s Covent Garden with the underground station and a horse and cart in the background in c.1930 and the same street in 2014. (Photo by Museum of London/Streetmuseum app)

A bulldog dressed as Marilyn Monroe poses for a photograph during the annual Tompkins Square Halloween Dog Parade in the Manhattan borough of New York City, October 24, 2015. (Photo by Stephanie Keith/Reuters)

Festival goers wear Australia day attire at Big Day Out 2012 at the Sydney Showground on January 26, 2012 in Sydney, Australia. (Photo by Mark Metcalfe/Getty Images)

Chinese-American actress Bai Ling attends “The Key” screening at The Real Experimental Film Festival at Laemmle's Music Hall on November 21, 2014 in Beverly Hills, California. (Photo by Barry King/WireImage)

Aerial acrobat Schindler, notorious for his foolhardy stunts, practising one of his tricks listing out of the vertical, from a Klemp plane piloted by Richard Perlia. (Photo by General Photographic Agency/Getty Images). Circa 1927

A mother bear takes a dip in the water to cool off in the warm summer sun but refuses to leave her three youngsters behind – so they climb aboard her back. (Photo by Jon Langeland/Solent News & Photo Agency)