The Survivors' Staircase was the last visible remaining original structure above ground level at the World Trade Center site. It was originally two outdoor flights of granite-clad stairs and an escalator that connected Vesey Street to the World Trade Center's Austin J. Tobin Plaza. During the September 11 attacks, the stairs served as an escape route for hundreds of evacuees from 5 World Trade Center, a 9-floor building adjacent to the 110-story towers.

On March 9, 2008, the Staircase was moved by crane about 200 feet on Vesey Street.[5] In 2010, as construction throughout the World Trade complex reached peak activity level, the staircase - as well as two "tridents" of Twin Tower facade, and other oversize artifacts - was placed into the National 9/11 Memorial Museum space before the Memorial Plaza and museum entrance pavilion were built above it. The staircase will be a major feature of the museum when it opens to the public in spring 2014. Source: Wikipedia