'Survivors' Stairs' And Other Mementos Of September 11

Two steel "tridents" recovered from the World Trade Center site after September 11, 2001, stand in the entry area of the Memorial Museum.

Construction continues around the last column of steel removed from the World Trade Center site in 2002.

The "Survivors' Stairs," on display in the museum, offered an escape onto the street from the World Trade Center Plaza, becoming a symbol of survival for hundreds of people.

A message is seen on the bottom of the "Cross," intersecting steel beams found in the rubble of 6 World Trade Center.

Steel facade segments, also known as "Impact Steel," that were torn apart when hijacked United Flight 175 struck the South Tower of the World Trade Center on September 11, 2001.

The burnt-out cab of a New York City Fire Department (FDNY) fire truck is seen inside the Memorial Museum.

A portion of the original steel footings embedded in the bedrock for the South Tower of the World Trade Center

A construction worker walks past two steel "tridents" recovered from the World Trade Center site after September 11, 2001, in the entry pavilion area of the new museum.

A message from a recovery worker appears on the wall inside the Memorial Museum.

The "Cross" (left), intersecting steel beams found in the rubble of 6 World Trade Center, and a fragment of a trident column that formed the exterior structure of the World Trade Center buildings

Steel from the wreckage of the September 11 disaster. Workers at the site have cut shapes out of the discarded steel to give as mementos to other workers and victims' loved ones.

Visitors to the September 11 Memorial Plaza peer through the windows of the Memorial Museum.