The 8-acre memorial — a tree-dotted plaza with waterfalls pouring into the Twin Towers footprints, surrounded by panels inscribed with the victims' names — has drawn visitors from all 50 states and 170 countries since it opened on the 10th anniversary of the attacks last year, memorial officials said.
“More than 4 million people visiting the 9/11 Memorial in less than one year is a remarkable milestone," 9/11 Memorial President Joe Daniels said in a statement.
"It reflects the deeply held belief of the importance of honoring victims of the terrorist attacks that shocked the world almost 11 years ago. These visitors who come to this site and walk this sacred ground are helping to preserve the memory of every man, woman and child taken from us too soon."
Visitors to the 9/11 Memorial must reserve a free, timed pass in advance.