On September 11, 2001, four commercial airliners were hijacked in a terrorist attack on America. As the 40 passengers and crew on United Airlines Flight 93 fought back against terrorists in the sky overhead, the plane crashed at 10:03 am, less than 20 minutes from the terrorists' intended target in Washington, DC. The field and woodlands surrounding the crash site are the final resting place of the passengers and crew of Flight 93. The site includes 40 Memorial Groves, each planted with 40 trees native to Pennsylvania, and the Tower of Voices, where 40 wind chimes pay tribute through sound. The Western Overlook is where the families of the passengers and crew gathered just days after the attack, and it also served as the FBI's temporary command post during the investigation.