Who cleans skyscrapers?
From our UK edition
Tough at the top The clocks on Big Ben were cleaned by abseiling window-cleaners. Some other big cleaning/painting jobs: — Repainting the Forth Railway Bridge used to be a metaphor for never-ending work, but a new coating completed in 2012 is estimated to have a life of 25 years. — Sydney Harbour Bridge was, for the first 80 years of its life, cleaned by hand, but last year it was done for the first time by robot. — The world's tallest building, the Burj Khalifa in Dubai, is cleaned by a team of abseilers, with all 24,000 windows taking three months to get through. — Most New York skyscrapers are cleaned by hand. The World Trade Center had an automated cleaner, but it could not cover the corners or upper windows. Two window cleaners were among the victims on 9/11.