No other construction site in America has proven to be more of a magnet than the 16 acres where the World Trade Center once stood. Two years after the unprecedented aerial terrorist attack demolished two of the world's tallest buildings, people from around the globe continue to be drawn to it. Some feel the need to see it to understand it. Others simply want to come to bear witness and honor the nearly 2,800 people who were killed in the attack that brought the 110-story buildings tumbling - explosively - to the ground. Today there is not much to see through the 10-foot-high fence other than trucks and cement mixers busy reinforcing the foundation and laying tracks for the new transit station. Plaques and photos that hang on the fence do provide an historic briefing about the development of the World Trade Center and the tragedy. Plenty of vendors hawk picture books, photos, and other 9/11 memorabilia. Yet nothing can replicate the overwhelming somberness that exists here. Like the event itself, it's almost impossible to comprehend.