A New York window cleaner strapped to the side of The RCA Building in the Rockefeller Center, with St Patrick's Cathedral below him to the left. (Photo by William Lovelace/Express/Getty Images). 2nd May 1961

A two-horse team street cleaner, with sprayer, squeegee, and roller at rear. New York, between ca. 1910 and ca. 1915. (Photo by NYC Municipal Archives)

A woman (L) places flowers at a grave next to a mummified body during exhumation works at the General Cemetery in Guatemala City, April 15, 2015. If a lease on a grave has expired or not been paid, grave cleaners will break open the crypts to remove and rebury the bodies. Any remains that have not been claimed are packed into plastic bags, labeled and stored in mass graves. Bodies that have been stored in the upper crypt are exposed to dry and sunny conditions which means they do not decompose and instead become mummified. (Photo by Jorge Dan Lopez/Reuters)

Young South Korean models, with wearable computers, walk the cat walk during the Ubiquitous Fashionable Computer Fashion Show on November 17, 2006 in Goyang, South Korea. (Photo by Chung Sung-Jun/Getty Images)

A participant works on a laptop on the first day of the 28th Chaos Communication Congress (28C3) – Behind Enemy Lines computer hacker conference on December 27, 2011 in Berlin, Germany. The Chaos Computer Club is Europe's biggest network of computer hackers and its annual congress draws up to 3,000 participants. (Photo by Adam Berry/Getty Images)