A portion of the World Trade Center slurry wall, left, and the symbolic last beam, are displayed at the National Sept. 11 Memorial Museum, Wednesday, May 14, 2014, in New York. The museum is a monument to how the Sept. 11 terror attacks shaped history, from its heart-wrenching artifacts to the underground space that houses them amid the remnants of the fallen twin towers’ foundations. It also reflects the complexity of crafting a public understanding of the terrorist attacks and reconceiving ground zero. (AP Photo)