September 11th, 2001. This Sunday marks the 15th anniversary of the worst terrorist attack on American soil.

Everyone who is old enough to remember that day can describe exactly where they were and what they doing when they heard the news of the first airplane -- piloted by terrorists -- hitting the World Trade Center in New York. They'll often talk about the picture-perfect blue skies that provided a backdrop for the planes, the fireballs and the smoke, soot and dust.

Not long after the first plane, a second aircraft crashed into the other tower at the World Trade Center and a third hit the Pentagon outside Washington -- leaving no doubt America was under attack.

The fourth plane, which was probably destined for Washington, was different. After United Flight 93 was commandeered by the terrorists, passengers started making phone calls to loved ones and learned of the other crashes. Even though they probably knew their fate, the 40 passengers decided to fight back.

When they stormed the plane's cockpit and wrestled with the hijackers, the plane crashed into the ground killing everyone on board. The passengers' heroism no doubt saved other lives.

The place where Flight 93 crashed was a windy, lonely field in Somerset County, Pennsylvania. Today, it is the site of the Flight 93 Memorial.

Friday's Smart Talk comes to you from that sacred ground.