A New York Police Department officer guards a door in front of 51 Park Place where debris from 9/11 is believed to have been found in New York, April 26, 2013. A piece of landing gear believed to be from one of the commercial airplanes that crashed into the World Trade Center on September 11, 2001, has been discovered, wedged between two lower Manhattan buildings, police said on Friday. [Photo: China Daily via Agencies]