Chiseled into granite:
"On September 11, 2001, acts of terrorism took the lives of thousands at the World Trade Center in New York City, in a grassy field in Shankesville, Pennsylvania and here at the Pentagon."
Mr. Rewrite also should note that there should be a comma after Pennsylvania regardless of whether the monument maker wants to follow AP style and abbreviate the state as Pa.
The article says the spelling will be corrected before the monument is unveiled. Woo-hoo.