How the National September 11 Memorial and Museum Works

Planning and Building the Memorial and Museum

September 11 memorial September 11 memorial
The two reflection pools at the memorial site sink into the footprints of the former twin towers and now serve as places of remembrance. James D. Morgan/Contributor/Getty Images

The design of the National September 11 Memorial & Museum is the work of architects Michael Arad and Peter Walker. Along with more than 5,000 other contenders, Arad and Walker submitted their design, called "Reflecting Absence," to the 2003 competition held to determine the look of the memorial. The judging panel was a 13-person Memorial Jury, which included the architect of the Vietnam Veterans Memorial, the curator of the Museum of Arts and Design, a 9/11 Memorial board member widowed in the attacks, a professor from the University of Massachusetts and the first deputy mayor of New York City, among others. The jury made its selection in January 2004 [source: The National September 11 Memorial & Museum].

The North and South Memorial Pools lie inside the footprints of the former twin towers. Located roughly between them is the pavilion entrance to the museum, designed by the Norwegian architecture firm Snøhetta. The architectural firm Aedas, working with Arad and Walker's design team, helped construct the memorial and the rest of the underground museum.

From the museum's glass atrium, visitors descend into a vast concrete sanctuary to tour the exhibits on display. Some are massive, like the Survivors' Stairs that allowed many to escape that day and the Last Column covered with remembrances during the cleanup efforts. Others are tiny, such as trinkets donated by the victims' families. Visitors can also see the location where the 1993 car bomb detonated and the slurry wall that held back the Hudson on 9/11.

And although now young, the 400-plus oak trees planted in the plaza are expected to grow to form a canopy over the memorial, providing a sense of stillness and calm fundamental to the memorial's goal: to allow visitors a place to mourn and reflect, to pay respects and find peace. A callery pear tree dubbed the Survivor Tree, which managed to survive the collapse in close proximity to the World Trade Center, has been nursed back to full health and will is on display.

In order to foster this urban forest, the design for the plaza features a suspended paving system. Between the roots of the trees and the museum, train station and other structures buried some 70 feet beneath the surface is a layer of loose soil — important for trees to thrive — rather than the compacted dirt commonly created during construction projects. Floating concrete tables give a safe walking surface around the plaza without squashing the dirt underneath and depriving the trees of access to nutrients and water. Thanks to this and other sustainability initiatives, the Memorial project hopes to attain Gold Leadership in Energy and Environmental Design (LEED) certification for sustainability.

But the journey from blueprint to building hasn't been without its ups and downs. Learn about some of the problems that have plagued the memorial and museum over the span of a decade.