Some of London's telephone operators and engineers, trying out their gas masks at the anti-gas civilian training centre in Gloucester, where they were taught how to deal with gas attacks. (Photo by Harry Todd/Fox Photos/Getty Images). 13th February 1937

Victoria's Secret angels Adriana Lima, Candice Swanepoel, Alessandra Ambrosio and Miranda Kerr arrive at the 2011 Victoria's Secret SWIM Collection Pink Carpet Event hosted by VS Angels at Club L on March 30, 2011 in Los Angeles, California. (Photo by Jerod Harris/Getty Images for Victoria's Secret)

Dameon Harris of Nevada gets used to the controls of a bulldozer at Dig This October 27, 2011 in Las Vegas, Nevada. At Dig This, tourists take a short class and can then operate full-size hydraulic excavators and track-type bulldozers in a giant sandbox while being guided by instructors over headsets. (Photo by Ethan Miller/Getty Images)

Julia Zlobina and Alexei Sitnikov of Azerbaijan gesture as they wait in the results area after competing in the ice dance free dance figure skating finals at the Iceberg Skating Palace during the 2014 Winter Olympics, Monday, February 17, 2014, in Sochi, Russia. (Photo by Vadim Ghirda/AP Photo)

In preparation for the Dubai Duty Free Men's Open, Andre Agassi and Roger Federer of Switzerland, couldn't resist the temptation to have a friendly “hit” on the world's most unique tennis court, the Helipad of the Burj Al Arab, the world's most luxurious hotel. Standing 321 metres high on a man made island, the majestic Burj Al Arab is without doubt the most recognizable hotel in the world. The hotel's helipad, which is situated 211 metres high covers a surface area of 415 square metres. The pictures were taken on February 22, 2005, in Dubai, United Arab Emirates. (Photo by Getty Images for Dubai Duty Free)

The Sugar Plum Fairy, Katherine Free, left, dances with the dog, Pig, during the Birmingham's Ballet “Mutt-cracker”, a rendition of the famous ballet “The Nutcracker”, in Birmingham, Alabama, December 8, 2016. (Photo by Brynn Anderson/AP Photo)

Workers pull apart a house in Khandyga, Russia, on February 2, 2018. The shifting ground caused by the uneven thawing of permafrost each summer causes buildings like this Soviet-era apartment house to sag and collapse. (Photo by Amos Chapple/Radio Free Europe/Radio Liberty)