Dubai - New Year Celebration at Burj Khalifa
postmarked in 2013 with three United Arab Emirates stamps
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Burj Khalifa known as Burj Dubai prior to its inauguration, is a skyscraper in Dubai, United Arab Emirates, and is the tallest man-made structure in the world, at 829.8 m (2,722 ft).
Construction began on 21 September 2004, with the exterior of the structure completed on 1 October 2009. The building officially opened on 4 January 2010.
In March 2009, Mohamed Ali Alabbar, chairman of the project's developer, estimated the total cost for the project to be about US$1.5 billion.
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To wash the 24,348 windows, totaling 120,000 m2 (1,290,000 sq ft) of glass, a horizontal track has been installed on the exterior of Burj Khalifa at levels 40, 73, and 109. Each track holds a 1,500 kg (3,300 lb) bucket machine which moves horizontally and then vertically using heavy cables. Above level 109, up to tier 27 traditional cradles from davits are used. The top of the spire, however, is reserved for specialist window cleaners, who brave the heights and high winds dangling by ropes to clean and inspect the top of the pinnacle. Under normal conditions, when all building maintenance units will be operational, it will take 36 workers three to four months to clean the entire exterior façade.
Unmanned machines will clean the top 27 additional tiers and the glass spire. The cleaning system was developed in Melbourne, Australia at a cost of $8 million.