Tuesday night at sunset, when the crowds of tourists and workers had long since departed, Lt. William Keegan, who led the recovery effort, took the families into the pit -- on the site where 2,823 people died.
"I think that when they come down here and feel the breeze going through you, and it's so quiet and its so large you feel that emptiness inside you is here," said the Port Authority police officer.
Linda Fergus' husband, Edward, was on the 104th floor of Tower One. She brought her two children to stand on the very ground where her husband's office once towered above.
"My kids are walking around in amazement and they didn't find my husband, so, to them, I think this is something they can take in and say, alright, he's gone. ... They have been asking to come down here for months," she told CBS News Correspondent Mika Brzezinski.
"My son is breaking down a bit -- my husband was his idol," she added.
Julie Burke lost her husband Thomas, just after the birth of their fourth son. She shielded her boys from the horrors of Sept 11, never letting them see the images of towers falling. The two oldest used to visit the towers often, going with their father to work.
As they walked around Burke noted, "Brian picked up something that look like a piece of tile and said it might be from the cafeteria at dad's office and he tucked in my purse."
And while so little physically is left at the site, the area holds so much for these families.
"This was where he was and the last time he was alive," said Burke. "It's the closest thing we can get to that. This is scared ground. It's part of our history now -- part of our family history."