As diplomats from around the world gather this week at the United Nations headquarters in New York City for the annual General Assembly meeting, they are encountering a rare sight: scaffolding hung from buildings� exteriors. After years of intense preparation, the 17-acre U.N. campus is undergoing its first major renovation since it was erected along the East River shortly after World War Two. The sweeping renovation won�t come cheap, at $1.87 billion, with the cost to be split among all 192 member nations. But when it�s complete in 2015, the five-structure complex, whose 11-member design team included Le Corbusier, Oscar