U.S. Interior Secretary Ken Salazar promised the memorial would be completed by the 10th anniversary of the terrorist attacks that also toppled the World Trade Center twin towers in New York and damaged the Pentagon in Washington.
"On behalf of a grateful nation, we say to the men and women of Flight 93 who gave their lives on Sept. 11, 2001, to prevent terrorists from attacking our nation's capital 'We will never forget you,'" Salazar
said. "This national memorial will always stand to honor you and to remind future generations that you fought and were victorious over the forces of evil."
The plane, flying from Newark, N.J., to San Francisco, was one of four planes hijacked in 2001. The 40 passengers, who knew from cell phone conversations, that hijackers had flown into the World Trade Center and the Pentagon, decided to retake the plane or bring it down.
Investigators believe the hijackers intended to aim the plane at the Capitol or White House.
Pennsylvania Gov. Ed Rendell and U.S. Sen. Bob Casey, D-Pa., also attended the ceremony.