... 

It extends deep below the memorial in a series of cavernous, hangar-like rooms. Its galleries contain crushed fire trucks, mangled steel, multimedia displays, a torn seatbelt from one of the airplanes that hit the towers, clothing and bicycles covered with ash from their collapse, photographs, architectural models and literally thousands of other pieces of dark memorabilia.

The intensity, scope and sheer unrelenting literalism of this approach marks a significant change in how we choose to mark national trauma. No longer do we see memorials as capable of commemorating an entire war or attack on their own.

Though there are now plans to add one, there was no museum accompanying Maya Lin's Vietnam Veterans Memorial when it opened in Washington, D.C., in 1982. Nearby, Friedrich St. Florian's neoclassical National World War II Memorial, completed in 2004, also stands by itself.

These days we see the symbolic shorthand that art and architecture have always relied on to deal with violence and tragedy as wildly insufficient.

Instead we've embraced some crowd-pleasing mixture of authenticity, easily digested narrative and insta-history. We want to see and touch the Real Thing, and we want somebody to explain to us what the Real Thing means.