In 1963 , Dr. Martin Luther King referenced the Alleghenies — among several in an evocative list of mountains — in his famous " I Have a Dream " speech , when he said " Let freedom ring from the heightening Alleghenies of Pennsylvania ! " The Flight 93 National Memorial is located at the site of the crash of United Airlines Flight 93 — which was hijacked in the September 11 attacks — in Stonycreek Township , Pennsylvania , about north of Shanksville . The memorial honors the passengers and crew of Flight 93 , who stopped Al-Qaeda terrorists from reaching their intended target
September 11 attacks
September 11 attacks
Allegheny Mountains