A Tribute WTC docent leads a guided walking tour of the 9/11 Memorial (Gary Cirlin photo; courtesy of Tribute WTC)
9/11 Memorial architect Michael Arad (photo courtesy of Handel Architects)
Mayor Bloomberg sits on a custom-built chopper Paul Jr. designed to commemorate the rebuilding at the World Trade Center site. (Ed Reed photo file)
A world map covered in blue represents from which countries visitors have either gone to see the 9/11 Memorial or planned a future visit. (Photo illustration by Kai Twanmoh)
The OEM helmet Richard Sheirer wore on 9/11.
Bronze panels honoring the victims of Flight 93 at the National September 11 Memorial. (Amy Dreher photo)
The aftermath of the World Trade Center attack. (Photo by Roberto Rabanne)
Chief Curator Jan Ramirez talks about a first responder vehicle recovered from the World Trade Center site. (file photo/Amy Dreher)