“Not for the faint of heart”. Casa Milà, better known as La Pedrera, is a building designed by the Catalan architect Antoni Gaudí and built during the years 1905–1910, being considered officially completed in 1912. It is located at 92, Passeig de Gràcia in the Eixample district of Barcelona, Catalonia, Spain. (Photo by Stefano Scarselli)

A rare turquoise mosaic mask is displayed at The Britrish Museum on April 7, 2009 in London, England. The Aztec mask, originally from Mexico will be one of the key exhibits to go on show at the Moctezuma: Aztec Ruler exhibition which opens to the public on 24 September 2009. (Photo by Dan Kitwood/Getty Images)

An installation entitled “Take my lightning but don't steal my thunder” by British artist Alex Chinneck stands in Covent Garden on October 2, 2014 in London, England. The installation is intended to cast the illusion that a 40-foot section of the Covent Garden's 184-year old market building is floating. “Take my lightning but don't steal my thunder” will be on display from 2nd to 24th October 2014. (Photo by Rob Stothard/Getty Images)

“Man is least himself when he talks in his own person. Give him a mask, and he will tell you the truth”. – Oscar Wilde. (Photo by Lala Roe)

Dancers at the Windmill Theatre in London, England practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)

A death mask thought to be that of English dramatist William Shakespeare (1566–1616). Found by Dr. Ludwig Becker in Mainz in 1849, the mask was linked to Shakespeare because of its 1616 date and its supposed facial resemblance to the writer. A rival theory, however, maintains that the mask is more likely to be that of English poet Ben Johnson. (Photo by Hulton Archive/Getty Images). Circa 1900

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