Ten years ago, when the World Trade Centers were attacked, officials closed areas below 14th Street in Manhattan where debris from the towers' collapse coated everything in gray.
Now, a decade since 9/11, everything seems to have returned to normal. But do people feel safer working, living and traveling here?
10 years of progress: An interview with Afghan ambassador to China
Video: Huang Junliang & Liu Yuhan
Producer: Flora Yue & Ji Tao