Visitors look over the waterfalls at the National September 11Memorial and Museum, Monday, Feb. 25, 2013 in New York. Tuesday will mark the 20th anniversary of the terrorist bombing ben

 

              Visitors look over the waterfalls at the National September 11Memorial and Museum, Monday, Feb. 25, 2013 in New York. Tuesday will mark the 20th anniversary of the terrorist bombing ben
Visitors look over the waterfalls at the National September 11Memorial and Museum, Monday, Feb. 25, 2013 in New York. Tuesday will mark the 20th anniversary of the terrorist bombing beneath the World Trade Center that killed six people in 1993. (AP Photo/Mark Lennihan)